Olivier Costa

Awenig Marié

Is there an alternative to consensus? The impact of the 2014 coalition deal on voting behaviour in the eighth European Parliament (2014-2019)

Consensus is a key feature of the European Union. In the European Parliament, most of texts are adopted by a grand coalition between the left and the right. While this trans-partisan cooperation has always been informal, the EPP and S&D groups agreed on a formal political coalition in 2014. For the first time in the EP's history, this grand coalition was based on a policy programme negotiated by the two groups' leadership. Based on roll-call vote data, this paper aims to understand the impact of this deal on actual coalition-building in the EP plenary.

We find that the 2014 coalition deal provided a framework incentivising legislative actors to increase cooperation on issues on which they usually cooperate the least.

Introduction

Consensus and compromise-building are a key feature of the European Union (EU) policymaking process [START_REF] Dehousse | Constitutional Reform in the European Community: Are There Alternatives to the Majoritarian Avenue?[END_REF][START_REF] Costa | The European Union as consociation? A methodological assessment[END_REF]. Consensual norms of interinstitutional negotiation, the politics of expertise and bargaining, as well as problem-solving approaches, have been gradually institutionalised within the EU machinery [START_REF] Elgström | Negotiation in the European Union: Bargaining or Problemsolving?[END_REF][START_REF] Radaelli | The public policy of the European Union: whither politics of expertise?[END_REF][START_REF] Reh | The Informal Politics of Legislation: Explaining Secluded Decision Making in the European Union[END_REF] and dominate the decision-making process within and between the EU institutions. The recent crises in the EU since the mid-2000s have further revealed the importance of inter-governmental settings, where national governments bargain with one another and where decisions are taken unanimously [START_REF] Bickerton | The New Intergovernmentalism: European Integration in the Post-Maastricht Era[END_REF][START_REF] Puetter | Europe's deliberative intergovernmentalism: the role of the Council and European Council in EU economic governance[END_REF], therefore putting aside overt forms of political conflict.

The consensual approach to policymaking at the EU level may conflict with the partisan and political nature of the European Parliament (EP), an electorally connected institution where individual members organise themselves along ideological lines and where party groups have been increasingly powerful over the last few decades [START_REF] Brack | Democracy in parliament vs. democracy through parliament? Defining the rules of the game in the European Parliament[END_REF]. Political conflict in the EP, which is more visible than in the other EU institutions (e.g., [START_REF] Novak | The silence of Ministers: Consensus and Blame Avoidance in the Council of the European Union[END_REF][START_REF] Mattila | Why Unanimity in the Council?: A Roll Call Analysis of Council Voting[END_REF], may be captured by voting dynamics in plenary. The literature finds that voting in the EP is determined by ideology and not nationality, and that the major division is between the left and the right [START_REF] Kreppel | Coalition Formation in the European Parliament[END_REF]. The left-right dimension of competition is more important to explain coalition-building than the anti-/pro-EU dimension [START_REF] Attinà | The Voting Behaviour of the European Parliament Members and the Problem of the Europarties[END_REF][START_REF] Raunio | The European Perspective: Transnational Party Groups in the 1989-94 European Parliament[END_REF][START_REF] Hix | Democratic Politics in the European Parliament[END_REF], confirming the fact that political conflict in the EP is arranged along the traditional left-right cleavage that structures most of the parliaments in established democracies.

Although the left-right cleavage is a strong determinant of coalition-building in the EP [START_REF] Hix | What's Wrong with the European Union and How to Fix It[END_REF], trans-partisan consensus between the left and the right also plays a crucial role [START_REF] Settembri | Achieving consensus through committees. Does the European Parliament manage?[END_REF][START_REF] Burns | Consensus and compromise become ordinary -but at what cost? A critical analysis of the impact of the changing norms of codecision upon European Parliament committees[END_REF]Tsebelis & Garett, 2000). Norms and practices of consensus are present at very different levels in the EP: in the plenary, committees, national delegations and party groups. Members of the EP (MEPs) have strong incentives to cooperate one with another in order to find large agreements, especially if they want to see their political career advance in the institution [START_REF] Bendjaballah | Des illusions perdues ? Du compromis au consensus au Parlement européen et à la chambre des représentants américaine[END_REF]. As a result, most of the legislation is adopted by a coalition between the centre-right (Group of the European People's Party -EPP) and the centre-left (Group of the Progressive Alliance of Socialists and Democrats in the European Parliament -S&D) groups (Hix et al., 2007, p. 159;[START_REF] Novak | Enduring consensus: why the EU legislative process stays the same[END_REF]. Between 2004 and 2014, around 70% of the plenary votes were adopted by a grand coalition between the EPP, the S&D, and the liberal ALDE (Alliance of Liberals and Democrats for Europe group) groups [START_REF] Hix | Empowerment of the European Parliament[END_REF]. In sum, consensus between the left and the right is very important in the EP for adopting regulation [START_REF] Novak | Enduring consensus: why the EU legislative process stays the same[END_REF], despite the growing politicisation of EU issues [START_REF] Hooghe | A Postfunctionalist Theory of European Integration: From Permissive Consensus to Constraining Dissensus[END_REF][START_REF] Börzel | From the Euro to the Schengen Crises: European Integration Theories, Politicization, and Identity Politics[END_REF].

Until recently, the consensus between the left and the right was not subject to any political agreement but was driven by a day-to-day cooperation for the adoption of regulation.

This changed in 2014. After the 2014 European elections, the EPP and S&D groups formed a political coalition whose aim was to support the policy action of the newly elected president of the European Commission Jean-Claude Juncker. This paper assesses whether and under which conditions a formal political agreement has any effect on actual coalition-building in the EP.

Drawing on two explanations of coalition-building in the EP, political actors' interest and their ideology, we expect the 2014 coalition agreement to have increased cooperation between the EPP and S&D groups only on votes where the two groups usually have a low interest to cooperate and where they tend to have diverging views. Using roll-call votes (RCVs) data, we study the voting behaviour of party groups in the EP plenary during the eighth legislative term (2014)(2015)(2016)(2017)(2018)(2019). Focusing on this period is relevant to our research question: while the first half of the eighth term was characterised by the presence of a political agreement between the EPP and S&D groups, this agreement ended in the middle of the term, in January 2017, when the Socialists voted against the EPP candidate for the EP presidency.

Analysing whether a coalition agreement affects coalition-building in the EP bears normative implications. This question taps into the broader issues of political representation and democratic accountability. First, if policy decisions continued to be adopted after the end of the agreement as often by a majority comprising the former coalition members (EPP and S&D), that would create a gap between the willingness of legislative actors to put an end to a formal coalition configuration and their actual behaviour. Second, the enduring high level of consensus would also limit the politicisation of EU issues, an element which contributes to media coverage and, ultimately, to a better articulation of citizens' demands into policy outcomes (e.g., [START_REF] Morales | The Gap between Public Preferences and Policies on Immigration: A Comparative Examination of the Effect of Politicisation on Policy Congruence[END_REF]. Finally, grand coalitions between the right and the left, and its subsequent suppression of overt political conflict and opposition [START_REF] Brack | S'opposer au sein du Parlement européen: Le cas des eurosceptiques[END_REF], may reduce the possibility for voters to make their representatives accountable [START_REF] Plescia | Who's to blame? How performance evaluation and partisanship influence responsibility attribution in grand coalition governments[END_REF] and may decrease the incentive for political parties to provide a clear and distinct policy platform [START_REF] Mair | Political Opposition and the European Union[END_REF].

In this paper, we analyse whether the presence of a formal political agreement between the EPP and S&D groups had any effect on the level of cooperation in plenary between these two groups. We do not include the liberal ALDE group in our analysis, even though it was included -albeit later -in the grand coalition formed in 2014. Indeed, in the vast majority of cases, when the EPP and S&D groups vote together, the liberal group is also on board.1 Also, the ALDE group is a pivotal group and a necessary partner for either the EPP or the S&D when these two groups oppose each other. In short, only the EPP-S&D cooperation is needed for analysing the general structure of competition in plenary (consensual or conflictual), and whether it was affected by the 2014 coalition agreement.

The importance of trans-partisan consensus in the European Parliament

The long-standing cooperation between the Christian Democrats and the Socialists

Since the 1960s, with the creation of an independent group by the Gaullist MEPs (RDE), the competition in the EP has been structured by the ideological left-right cleavage. Although they are not on the same ideological side, the Socialists and the Christian Democrats have always showed a certain capacity to cooperate, especially when voting in plenary. The literature provides five lines of explanation for this. First, the two groups converge on the main aspects of European integration, such as the scope of the integration project, its necessary institutions, and some key policies [START_REF] Hix | Democratic Politics in the European Parliament[END_REF]. Second, they have a common interest in controlling the EP and, therefore, impose to other party groups "pre-cooked" decisions in order to control the leadership organs and the EP overall organisation [START_REF] Westlake | A Modern Guide to the European Parliament[END_REF][START_REF] Brack | Democracy in parliament vs. democracy through parliament? Defining the rules of the game in the European Parliament[END_REF]Hix et al., 200;[START_REF] Corbett | The European Parliament[END_REF]. Third, the EPP-S&D cooperation is explained by institutional constraints and the need for the assembly to find large majorities because of treaty requirements (an absolute majority of members is required to adopt amendments to the budget or legislative amendments in second reading or to 'elect' the President of the Commission) [START_REF] Corbett | The European Parliament[END_REF]. Four, some consider that parliamentary actors have an interest in finding large majorities in order to have a stronger stance in interinstitutional negotiations [START_REF] Corbett | The European Parliament's Role in Closer EU Integration[END_REF][START_REF] Hix | Political Parties in the European Union[END_REF][START_REF] Kreppel | Coalition Formation in the European Parliament[END_REF]. Finally, the rise of Eurosceptics in the EP may force pro-European groups to cooperate more if they want to limit the legislative influence of anti-EU MEPs [START_REF] Brack | Euroscepticism at the supranational level: the case of the 'untidy right' in the European Parliament[END_REF]. Until 2014, there was no formal political agreement between the Christian democratic and the socialist groups in the EP. The two groups used to informally work together in order to "co-manage" the EP and to coordinate their positions both on the EP internal affairs and on specific policies [START_REF] Corbett | The European Parliament[END_REF]. This cooperation has been formalised in a technical and non-political agreement at the occasion of the election of the EP President. A first technical agreement was negotiated after the 1989 European elections in order to avoid the situation experienced in 1982 and 1987, where the lack of coordination led to the success of candidates who did not make the best score in the first round. the Christian democrats and the Socialists decided to share the EP presidency by organising it through time: they agreed to support a single candidate at the beginning of the term and another one at mid-term. This agreement included other arrangements regarding the overall functioning of the EP, and especially the appointment of vice-presidents and committee chairs. However, before 2014, technical agreements only aimed at ensuring a smooth coordination of the EP organisation and did not include any policy objectives. In that respect, technical agreements differ from the constraining political coalition agreements that are common in many countries (e.g., [START_REF] Moury | Coalition Government and Party Mandate. How Coalition Agreements Constrain Ministerial Action[END_REF].

The formal political coalition during the eighth legislative term

In 2014, for the first time in the EP's history, a formal political coalition has emerged between the EPP and S&D groups. Soon after the 2014 European elections, the two leaders of the right and the left, Jean-Claude Juncker (EPP) and Martin Schulz (S&D), agreed on a coalition that would back Juncker for the presidency of the European Commission and that would be "based on a programme agreed by both sides" (Penalver Garcia and Priestly, 2015, p. 153). The negotiation between the EPP and S&D groups in 2014 was very political and not only technical. Although the deal did not include a formal written agreement, the two groups discussed and agreed on policy provisions for the Juncker's mandate. As a result, the priorities highlighted by Juncker in his program for the Commission presidency included policy proposals that are usually advocated by the Socialists and the Liberals (Penalver Garcia & Priestley, 2015, p. 168). The liberal ALDE group later joined the coalition. The 2014 coalition agreement may be explained several factors.

The first factor is the Spitzenkandidaten process and relates to the defence of the EP's institutional interests. While the five main groups (S&D, EPP, ALDE, GUE and Greens) agreed to organise the 2014 European elections around a competition between their respective candidate for the presidency of the European Commission (the Spitzenkandidaten process), their initiative received some scepticism in the European Council, as most of the heads of state and government wanted to maintain the right to propose their own candidate [START_REF] Christiansen | After the Spitzenkandidaten: fundamental change in the EU's political system?[END_REF]Penalver Garcia & Priestly, 2015). Immediately after the election, the EPP, S&D and ALDE groups agreed to claim the appointment of Jean-Claude Juncker (candidate of the EPP party) at the presidency of the Commission. This high level of internal cohesion within the parliament allowed the institution to defend its interests and the whole Spitzenkandidaten process vis-à-vis the European Council.

The second factor relates to the increasing presence of Eurosceptic forces in the EP [START_REF] Brack | Introduction: Euroscepticism, from the margins to the mainstream[END_REF]. The rise in the number of Eurosceptic MEPs, as well as their growing willingness to dedicate more time to legislative activities [START_REF] Behm | Sheep in wolf's clothing? Comparing eurosceptic and noneurosceptic MEPs' parliamentary behaviour[END_REF], may have incentivised pro-EU groups to coalesce more in order to limit the legislative influence of Eurosceptic forces.

Third, the grand coalition agreement in 2014 may be explained by the close personal relations between party leaders. The excellent relationship between Jean-Claude Juncker and Martin Schulz (Penalver Garcia & Priestley, 2015, p. 165), as well as with the liberal leader Guy Verhofstadt, has certainly eased the negotiations in view of the formalisation of the grand coalition. The ideological position of Jean-Claude Juncker (social Christian centrist), who distanced himself from the EPP's manifesto on some economic and migration issues, may have also appealed to the Socialists and contributed to the S&D group accepting to cooperate and to form a grand coalition (Penalver Garcia & Priestley, 2015, p. 169).

Finally, the 2014 agreement may result from institutional routines. Although this formal coalition is very new for the EP, it does not come from nowhere: EPP and S&D groups have been used to negotiate "technical agreements" and to cooperate for adopting legislative reports for some decades [START_REF] Hix | The Party System in the European Parliament: Collusive or Competitive?[END_REF]. In our dataset of roll-call votes in the plenary, 93% of the legislative reports during the 7 th term (2009-2014) were adopted by a coalition between the EPP and the S&D. Therefore, in 2014, the two groups may have preferred a grand coalition arrangement that has already been informally tested rather than to form an alternative coalition which was not present in the near institutional memory [START_REF] Lees | The Grand Coalition and the Party System[END_REF].

The coalition agreement ended during the mid-term shake-up of top jobs, in January 2017. The breakdown of the deal resulted from the Socialists' decision to present their own candidate for the EP presidency, while it was agreed that the EPP would get it during the second half of the term2 . With a very contested election (Antonio Tajani was elected after third rounds of voting), media and commentators predicted a new era of decision-making, more political and polarised between the left and the right. These changes raised concerns about the capacity of the Juncker Commission to build majorities in the EP for adopting its legislative proposals, since they had been previously agreed by the members of the grand coalition and were inserted in the 2014 Work Programme.

The impact of a political agreement on coalition-building in the EP

This paper assesses whether and under which conditions a formal political agreement has any effect on actual coalition-building in the European Parliament. Overall, we expect the agreement to have affected the EPP-S&D cooperation in the EP plenary. While the two groups had an interest in forming this coalition in 2014, it was even more in their interest to make this deal work in the day-to-day decision-making process. Specifically, with the rise of Eurosceptic forces in the assembly, the EPP and S&D groups are expected to have increased their cooperation in order to provide the newly elected Juncker Commission a stable legislative environment for implementing the policy programme that was agreed in 2014. Moreover, this formal agreement may have created institutional constraints for legislative actors. Although it did not include control mechanisms for coalition partners to keep an eye on each other, as this can be the case in other legislatures (Strøm & Muller, 1999;[START_REF] Timmermans | Standing apart and sitting together: Enforcing coalition agreements in multiparty systems[END_REF], the agreement between the EPP and the S&D can be considered a general framework that incentivised and constrained legislative actors from these two groups to work closely more than they used to do and, at the end of the legislative process, to show a united front when voting in the EP plenary.

Therefore, one may expect the cooperation between the EPP and S&D groups in the plenary to have increased as a result of the coalition agreement.

However, drawing on past research on coalition-building in the EP, we argue that the effect of the coalition agreement on the EPP-S&D cooperation should depend on several contextual factors. In other words, the agreement should not have affected all votes to the same extent. We rely on two explanations of coalition-building in the EP: the role of political actors' interest and that of ideology.

Firstly, the two groups have cooperated a lot in the past few decades [START_REF] Hix | Democratic Politics in the European Parliament[END_REF][START_REF] Hix | The Party System in the European Parliament: Collusive or Competitive?[END_REF] because they had an interest in doing so: to present a united front to the other EU institutions, to deal with the increasing fragmentation of the legislature, and to co-manage the internal organisation of the EP (see [START_REF] Kreppel | Rules, Ideology and Coalition Formation in the European Parliament[END_REF][START_REF] Westlake | A Modern Guide to the European Parliament[END_REF]. However, this strong interest for cooperation between the left and the right does not apply equally to all types of votes. Specifically, while the EPP and S&D groups might have an interest to cooperate in some cases, it is also in their interest to increase political conflict in others. Therefore, we expect the 2014 coalition agreement to have increased cooperation only on votes where the two groups usually have a low interest to cooperate. On the contrary, it should not have affected cooperation on votes where the EPP an S&D groups usually show a strong interest in cooperation. We develop more specific hypotheses regarding the effect of the 2014 agreement cooperation on legislative files, non-legislative files, and internal matters.

First, we do not expect the 2014 agreement to have affected coalition-building on legislative files. The EPP and S&D groups are indeed policy-seeking actors who "co-manage" the policymaking process: they get most of the rapporteurship on important dossiers, build on policy expertise and spend time and resource to negotiate in informal trilogue meetings with Council's representatives. They benefit from decision-making efficiency and, therefore, traditionally cooperate more often on legislative files [START_REF] Høyland | Procedural and party effects in European Parliament roll-call votes[END_REF][START_REF] Hix | The Party System in the European Parliament: Collusive or Competitive?[END_REF][START_REF] Kreppel | Rules, Ideology and Coalition Formation in the European Parliament[END_REF]. Moreover, trans-partisan cooperation is crucial for reaching the absolute majority threshold required to reject or to amend the Council's position at second reading [START_REF] Hagemann | Bicameral Politics in the European Union[END_REF]Corbett et al., 1995). Finally, since the EU is a bicameral system [START_REF] Costello | Does Bicameralism Promote Stability? Inter-institutional Relations and Coalition Formation in the European Parliament[END_REF], trans-partisan cooperation is also a way for the EPP and S&D groups to increase the whole legislative influence of the EP vis-à-vis the Council [START_REF] Hix | The Party System in the European Parliament: Collusive or Competitive?[END_REF][START_REF] Burns | Consensus and compromise become ordinary -but at what cost? A critical analysis of the impact of the changing norms of codecision upon European Parliament committees[END_REF], something we may refer to as "institutional patriotism" [START_REF] Novak | Enduring consensus: why the EU legislative process stays the same[END_REF]. Both groups have an interest in cooperating if they want to show a united front in inter-institutional trilogue meetings [START_REF] Reh | The Informal Politics of Legislation: Explaining Secluded Decision Making in the European Union[END_REF]. In sum, regardless of whether there is a political agreement between them, the EPP and S&D groups should cooperate in the EP plenary in order to secure policy gains and to avoid giving Eurosceptic MEPs too much influence [START_REF] Mühlböck | The Council, the European Parliament, and the paradox of inter-institutional cooperation[END_REF][START_REF] Reh | The Informal Politics of Legislation: Explaining Secluded Decision Making in the European Union[END_REF].

Hypothesis 1: The voting cooperation between the EPP and S&D groups on legislative files was not affected by the 2014 coalition agreement.

Contrary to legislative files, we expect the coalition agreement to have increased consensus on non-legislative files, on which the interest to cooperate is usually lower. On these files, MEPs do not need to show a united front in inter-institutional negotiations and are never required to reach an absolute majority threshold. Also, the EPP and S&D groups may have an interest in increasing political conflict on non-legislative files. Because their credibility is not at risk if one of these files fails to be adopted, they use them to signal their policy preferences to their voters. This is even more likely as the EU elections get closer [START_REF] Lindstädt | Balancing competing demands: Position taking and election proximity in the European Parliament[END_REF]Koop et al., 2017). Therefore, while MEPs and party groups are expected to have been incentivised to increase cooperation on non-legislative files when the coalition agreement was in place, they had no interest in keeping voting together after it fell apart in 2017.

However, this general expectation about non-legislative files should depend on the report's inter-institutional implications. The EPP and S&D groups have a lower interest in cooperating when implications are low. On the one hand, motions for resolution (RSP) are nonbinding declarations, often on high-profile issues that are beyond the legislative competences of the EU. Because MEPs use them for publicity, especially vis-à-vis their constituents [START_REF] Brack | Democracy in parliament vs. democracy through parliament? Defining the rules of the game in the European Parliament[END_REF], the interest to cooperate is rather low. On the other hand, own-initiative reports (INI) and legislative initiative reports (INL) are used by the EP to exercise its indirect right to initiate legislation (art. 225 TFUE) [START_REF] Maurer | European Parliament's Policy Department for Citizens' Rights and Constitutional Affairs[END_REF]. Although non-binding, these files formally request the European Commission to respond to the EP and allow parliamentarians to shape the policy agenda [START_REF] Kreppel | European Parliament resolutions-effective agenda setting or whistling into the wind?[END_REF]. The EPP and S&D groups have more interest in cooperating on these files, especially if they want to influence the Commission's legislative agenda. Therefore, while we expect the coalition agreement to have increased trans-partisan cooperation on motions for resolutions (RSP), we do not expect any effect on initiative files (INI and INL).

Hypothesis 2: The voting cooperation between the EPP and S&D groups on motions for resolution was positively affected by the 2014 coalition agreement, while their cooperation on initiative reports was not.

Finally, we do not expect the coalition agreement to have affected coalition-building on votes relating to internal matters. Indeed, the level of EPP-S&D cooperation has usually been very high on issues regarding the management of the internal affairs of the EP (Kreppel & Hix, 2003). This collusion is considered as a way for both groups to prevent the smaller groups from securing influence in the internal workings of the parliament (Corbett et al., 2000;[START_REF] Westlake | A Modern Guide to the European Parliament[END_REF]. The history of technical agreements in the EP perfectly illustrates this point. Therefore, the EPP and S&D groups should have an interest in managing the parliament regardless of the presence of a political agreement.

Hypothesis 3: The voting cooperation between the EPP and S&D groups on internal matters was not affected by the 2014 coalition agreement.

While legislative actors' interests determine coalition-building in the EP, ideology should also play a role (Hix et al., 2007, chapter 8;[START_REF] Guinaudeau | Issue Politicization in the European Parliament. An Analysis of Parliamentary Questions for Oral Answer[END_REF]. Because political actors have policy-oriented objectives, coalitions often form between groups that are ideologically close (De Swan, 1973). In the EP plenary, [START_REF] Kreppel | Rules, Ideology and Coalition Formation in the European Parliament[END_REF] found variation in coalition-building across different policy areas. Spatial models of parliamentary voting in the EP also suggest that the policy proximity between the EPP and the S&D is greater on issues related to the EU integration or international affairs than on socio-economic and socio-cultural issues (Hix et al., 2007, chapter 9;[START_REF] Hix | Voting patterns and alliance formation in the European Parliament[END_REF][START_REF] Hix | Changing Political Cleavages in Advanced Democracies: Evidence from the European Parliament[END_REF]. For instance, contrary to socio-economic and socio-cultural files, which may include redistributive provisions and produce winners and losers, international affairs' reports (instruments for pre-accession assistance, international trade, development aid) deal with the overall action of the EU vis-àvis non-EU countries and are more likely to be supported by a large and trans-partisan coalition in the EP. Therefore, we expect the 2014 coalition agreement to have increased the level of cooperation only in policy areas where the EPP and S&D usually have diverging views. On the contrary, when the two groups are ideologically close, the coalition agreement should not have affected their propensity to cooperate in plenary. Moreover, in addition to policy proximity between the EPP and S&D on files related to reforming the institutional set-up of the EU, the legislative behaviour of Eurosceptics is expected to drive up cooperation on these cases. Indeed, on EU-related reports, the systematic opposition of Eurosceptic MEPs [START_REF] Brack | S'opposer au sein du Parlement européen: Le cas des eurosceptiques[END_REF] should give extra incentives to the EPP and the S&D to vote together in plenary.

Hypothesis 4: The voting cooperation between the EPP and S&D groups was positively affected by the 2014 coalition agreement on socio-economic and socio-cultural issues, but not on issues related to the EU integration and on international affairs.

Data and methods

We test our hypotheses quantitatively on a dataset containing all the plenary roll-call votes (RCVs) from the eighth legislative term (2014)(2015)(2016)(2017)(2018)(2019). Our findings will be validated against data from the sixth (2004)(2005)(2006)(2007)(2008)(2009) and the seventh (2009)(2010)(2011)(2012)(2013)(2014) terms. The data was extracted from the EP's Public Register of Documents and additional contextual information (procedure, type of vote, committee) come from the Legislative Observatory website.

The use of RCVs data is very common in legislative studies. It has been used to measure MPs' ideological positions (e.g., [START_REF] Macrae | Dimensions of congressional voting: A statistical study of the House of Representatives in the Eighty-first Congress[END_REF], the issue congruence between legislators and their districts (e.g., [START_REF] Miller | Constituency Influence in Congress[END_REF], the internal cohesion of party groups, and intergroup cooperation (e.g., [START_REF] Depauw | Government Party Discipline in Parliamentary Democracies: the Cases of Belgium, France and the United Kingdom in the 1990s[END_REF]. Originally used in US Congress studies, RCVs studies have dominated the literature on the EP since the nineties (e.g. [START_REF] Attinà | The Voting Behaviour of the European Parliament Members and the Problem of the Europarties[END_REF][START_REF] Hix | Power to the Parties: Cohesion and Competition in the European Parliament, 1979-2001[END_REF][START_REF] Høyland | Procedural and party effects in European Parliament roll-call votes[END_REF][START_REF] Raunio | The European Perspective: Transnational Party Groups in the 1989-94 European Parliament[END_REF][START_REF] Otjes | The Eurozone crisis and the European Parliament's changing lines of conflict[END_REF][START_REF] Bowler | Political Group Cohesion and 'Hurrah' Voting in the European Parliament[END_REF] and have produced two main findings: the EP party groups display high levels of internal cohesion in plenary and the main cleavage structuring competition is the left-right dimension [START_REF] Kreppel | Coalition Formation in the European Parliament[END_REF]Hix et al., 2007, p. 94).

Yet the use of RCVs is not without its critiques. One of the main drawbacks is the selection bias [START_REF] Carruba | Off the Record: Unrecorded Legislative Votes, Selection Bias and Roll-Call Vote Analysis[END_REF][START_REF] Thierse | Going on record: Revisiting the logic of roll-call vote requests in the European Parliament[END_REF][START_REF] Clinton | Using Roll Call Estimates to Test Models of Politics[END_REF][START_REF] Hug | Selection Effects in Roll Call Votes[END_REF]. In most of the legislatures, not all votes are publicly recorded; in the EP, only final votes are systematically recorded -and this has not always been the case. For non-final votes, parliamentary groups often request a roll call in order to either discipline their own members or to make public their own position or the position of another group [START_REF] Thiem | Explaining Roll Call Vote Request in the European Parliament[END_REF]. RCVs samples are, therefore, not fully representative of the whole population of plenary votes. Although RCVs samples have recently become more representative, because of both changes in the EP's Rules of Procedure and the extension of the EP's legislative powers [START_REF] Kaniok | Roll Call Votes in the European Parliament: a good sample or a poisoned dead end?[END_REF], the conclusions reached on the basis of RCVs cannot be generalised to the whole population of plenary votes.

Moreover, those conclusions cannot be applied to other forms of legislative behaviour or interaction between party groups. Although roll call data provides us with an interesting picture of coalition-building in plenary, it says nothing about cooperation occurring during the pre-plenary steps of the policymaking process (co-sponsorship of amendments or resolutions, informal forms of exchange of information, cooperation between the committees' coordinators for the distribution of reports, agreements between group leaders on the EP's agenda and the overall inter-institutional strategy). Also, voting data does not shed light on voting behaviour in EP committees [START_REF] Hurka | Changing the output: The logic of amendment success in the European Parliament's ENVI Committee[END_REF]. One could expect, for instance, that the 2014 agreement did not affect coalition-building in committees since a smooth cooperation between the main groups has been these past years necessary to ensure the efficiency of the efficient legislative work [START_REF] Neuhold | The "Legislative Backbone" keeping the Institution upright? The Role of European Parliament Committees in the EU Policy-Making Process[END_REF][START_REF] Settembri | Achieving consensus through committees. Does the European Parliament manage?[END_REF].

This paper studies the impact of the 2014 coalition deal on the cooperation between the EPP and S&D groups in plenary. We measure this cooperation on each plenary vote. Our dependent variable is the EPP-S&D AGREEMENT INDEX, which captures whether the two groups cooperated on a given roll-call vote [START_REF] Hix | The Party System in the European Parliament: Collusive or Competitive?[END_REF]. The variable is dichotomous: it takes the value '1' if the plurality (relative majority) of MEPs from the two groups voted in the same way, '0' otherwise. The groups' majoritarian position can either be 'in favour', 'against', or 'abstention'. 3 We decided not to merge 'abstention' and 'against' since abstention can be considered as a genius choice for MEPs [START_REF] Mühlböck | When legislators choose not to decide: Abstentions in the European Parliament[END_REF]Font, 2018). On average, the EPP and S&D groups voted together in 72.4% of the time during the eighth term, 73.2% during the seventh term, and 69.3% during the sixth term.

Our main independent variable is the presence or absence of the Coalition deal during the eighth legislative term. The deal was in place from the beginning of the term (July 2014) until the month before the mid-term elections (January 2017). It was not reconducted for the remaining period. With this variable, we can compare the frequency of the EPP-S&D cooperation during two distinct periods, an approach similar to the one used by [START_REF] Kreppel | From 'grand coalition' to left-right confrontation. Explaining the shifting structure of party competition in the European Parliament[END_REF]. We developed four hypotheses on the effect of the 2014 coalition agreement on actual coalition-building in the EP. The coalition agreement is expected to have increased actual cooperation only on votes where the EPP and S&D groups usually have low interest in cooperating (non-legislative files, files without interinstitutional implications, votes not related to the EP's internal matters) and on votes where they disagree the most (socio-economic and socio-cultural issues). We use different independent variables for testing our hypotheses. First, a vote is Legislative if it is on a binding report adopted through the following procedures: the ordinary legislative procedure, the budgetary and discharge procedures, the delegated and implementing acts procedures, and the consultation and consent procedures. Second, Nonlegislative votes are the ones on motions for resolution and own-initiative reports. Votes on 3 The value is "in favour" if the number of MEPs from group X voting in favour is higher than the number of MEPs from group X abstaining and voting against. The same logic applies to the values "against" and "abstention".

Internal matters concern orders of business adopted in plenary and the amendments to the EP's Rules of Procedure. Finally, the Policy issue of a vote is determined by the committee responsible for drafting the report, following the approach of [START_REF] Hix | What to Expect in the 2009-14 European Parliament: Return of the Grand Coalition?[END_REF] and Kreppel and Tsebelis (1999, p. 958). Reports can either be on 'EU-integration issues', on 'International affairs issues', on 'Socio-economic issues', and on 'Socio-cultural issues' (see Appendix I).

The analysis in this paper is exploratory: we analyse whether coalition-building is different when the 2014 agreement was in place compared to when it was not. It consists of descriptive statistics. More specifically, we compare the mean of our EPP-S&D AGREEMENT INDEX for two time periods (when the Coalition deal was in place compared to when it was not). The different hypotheses will be tested against of the subset of the dataset containing only legislative votes, only non-legislative votes, or only votes on internal matters. Moreover, we separately study final and non-final votes because legislative actors' strategies and coalition patterns on these two types of votes is likely to differ [START_REF] Hix | The Party System in the European Parliament: Collusive or Competitive?[END_REF]Kreppel & Hix, 2003;[START_REF] Kreppel | Coalition Formation in the European Parliament[END_REF]. Indeed, the EPP and S&D groups are more likely to cooperate on final votes because of their inter-institutional implications. Final votes are those on the whole report, while non-final votes concern amendments, recitals, and paragraphs. We decided to use descriptive statistics and not regression analyses for three reasons. First, because our data is not a sample but contain the whole population of roll-call votes in the EP plenary, we believe it does not make much sense to have regression models with significance levels. Second, since the focus of our analysis is not on general trends but on coalition-buildings in different circumstances, we do not need a regression model estimating the general effect, on all roll-call votes, of the deal on the EPP-S&D cooperation. Finally, our analysis already takes into account control variables that are expected to have an independent effect on coalition-building in plenary (type of vote, type of file, policy area).

Results

Before delving into our hypothesis testing results, let us present the general evolution of the cooperation between the EPP and S&D groups in the EP plenary. Overall, the EPP and S&D groups cooperated on 76.5% of the plenary roll-call votes when the coalition agreement was in place, before January 2017, against 70.3% after the deal ended. This result is confirmed by the yearly evolution of the level of EPP-S&D cooperation. Figure 1 shows the cooperation rate between both groups for each year of the eighth term (blue line), as well as for each year of the sixth and seventh terms. The trend depicted in the graph confirms that the 2014 coalition agreement had an impact on actual coalition-building in plenary. The EPP-S&D cooperation gradually fell throughout the eighth term -from 79.1% in 2014 to 66.6% in 2019 -and, more specifically, after the fourth year, which marked the end of the agreement. To validate this finding, we compare this trend with those from the sixth and the seventh terms. We find that the decline in the level of EPP-S&D cooperation throughout the eighth term is not a systematic trend present in all legislatures.

[INSERT FIGURE 1]

Sources: Authors' data

In what follows, we test our four hypotheses related to the role of political actors' interest and ideology. Overall, we expect the coalition agreement to have increased the level of cooperation on issues where the EPP and S&D groups usually have a low interest in voting together (on non-legislative files, on files with low inter-institutional implications), and when they usually have diverging issues. On the contrary, the EPP-S&D cooperation should remain stable and very high when both groups have a strong interest in voting together (on legislative files, internal matters) and when they are ideologically close.

First, we expect the EPP-S&D cooperation on legislative files to be unaffected by the coalition agreement (H1). Overall, the EPP and the S&D voted together on 83.4% of the legislative files when the deal was in place against 72.5% after it broke down in January 2017.

However, when disaggregating the data by type of vote (vote on a final report or on amendments or articles) -an element that has been proven to affect coalition-building in the EP [START_REF] Kreppel | Rules, Ideology and Coalition Formation in the European Parliament[END_REF]Kreppel & Hix, 2003;[START_REF] Kreppel | Coalition Formation in the European Parliament[END_REF] -the results are more mixed. The lefthand panel of Figure 2 shows the yearly average cooperation rate on final votes during the eighth term, and the right-hand panel shows the average cooperation rate on non-final votes.

On the one hand, the trend for non-legislative files it not so clear. The EPP and S&D groups cooperated a lot during the first year of the legislative term, in 2014, but then opposed each other on legislative amendments in around 60% of the cases. On the other hand, the fall in cooperation on final legislative files is not meaningful. The two groups continued to have a close cooperation for adopting final legislative reports even after the end of the cooperation agreement in 2017: from 2017 to 2019, around 95% of final legislative reports were still adopted by a grand coalition between the left and the right. Our first hypothesis is thus confirmed by the data: the coalition agreement is not an instrument that significantly increased actual cooperation between the EPP and S&D groups on legislative files. That is not surprising, as it is on these files, especially on final legislative votes, that the interest to cooperate is the highest. The two groups, who put a high emphasis on legislative efficiency [START_REF] Brack | Democracy in parliament vs. democracy through parliament? Defining the rules of the game in the European Parliament[END_REF], have a common interest to get regulation adopted and, regarding final votes, should consider the importance of presenting a united front to the other EU institutions [START_REF] Kreppel | Coalition Formation in the European Parliament[END_REF].

[INSERT FIGURE 2]

Sources: Authors' data Second, regarding non-legislative files, we expect the effect of the 2014 coalition agreement to depend on the report's inter-institutional implications (H2). On the one hand, the EPP and S&D groups should cooperate no matter what on non-legislative files with high interinstitutional implications because they have an interest in showing a united front vis-à-vis the other EU institutions. On the other, because the stakes are lower on non-legislative files without inter-institutional implications, the level of cooperation is expected to have increased on these files as a result of coalition agreement. Figure 3 shows the average cooperation rate for votes on final non-legislative reports with both higher and lower inter-institutional implications.

Our hypothesis is supported by the data. On the one hand, the coalition agreement did not affect the EPP-S&D cooperation on non-legislative reports with higher inter-institutional implications: the proportion of these reports adopted by the grand coalition stayed identical after the end of the agreement. This illustrates the importance for the two groups to reach broad majorities in order to increase the EP's initiative power independently of the political agreement signed in 2014. On the other hand, the end of the agreement had a sizeable effect on the adoption of non-legislative reports with low inter-institutional implications: the EPP-S&D cooperation on these files decreased from 78% to 61%. Because motions for resolution are used by groups to communicate to their voters a specific position, both groups have an interest in increasing political conflict, especially when there is not a political agreement. Therefore, our data suggests that the agreement provided either incentives or constraints for the two groups to cooperate more on non-legislative reports with low inter-institutional implications.

[ INSERT FIGURE 3]. Third, we do not expect the coalition agreement to influence coalition-building on votes regarding the EP's internal affairs (H3), since the EPP and S&D groups have been co-managing the EP's internal business for more than three decades. Because they have a strong interest in voting together on reports dealing with the EP's internal organisation regardless of the presence of a coalition deal, they should not have stopped cooperating on these votes after the end of the agreement in 2017. Figure 4 shows the average EPP-S&D cooperation rate on two types of votes dealing with the EP's internal affairs: orders of business and amendments to the EP's Rules of Procedure (REG).

[ INSERT FIGURE 4] We do not find a general pattern for internal matters votes. First, the 2014 agreement increased cooperation on order of business items. These items are put forward at the beginning of each session by legislative actors which want to add to the agenda points of debate regarding non-legislative dossiers, for instance cases of breaches of human rights or rule of law issues.

Here, the interest for the two groups to cooperate is low: these topics are often beyond the competences of the EU and are, therefore, used to signal a position to voters. In line with the interest-based explanation of coalition-building, we find that the coalition agreement increased the EPP-S&D cooperation on these votes. Specifically, while the EPP and S&D groups were bound by the agreement between 2014 and 2017, or had higher incentives to work hand in hand, they no longer had an interest in voting together on these files after the agreement fell apart.

Second, as expected, votes on amendments to the rules of procedure (REG) were not affected by the coalition agreement. In nearly all cases, they were adopted by a grand coalition between the left and the right. These files are examined by the Committee on Constitutional Affairs (AFCO) and are adopted in the EP plenary with an absolute majority (art. 232 TFEU). The EP's Rules of Procedure structure the actual organisation of the parliament and define the rules of the game for the different legislative actors. The many reforms of the EP's rules have been used to rationalise the deliberation of the assembly as to increase its overall influence in the EU's political system [START_REF] Brack | Democracy in parliament vs. democracy through parliament? Defining the rules of the game in the European Parliament[END_REF]. The EPP and S&D groups have a strong interest in co-managing the internal organisation of the institution and, therefore, cooperate when it comes to amending the institution's rules. This was already the case in the 1980s, thanks to the "technical agreement" and, as showed by our data, does not depend on a formal political agreement between the left and the right.

In sum, the coalition deal did not increase the convergence of votes on internal matters dealing with the EP's rules of procedure. Regardless of the existence of an agreement, the two groups were constant in cooperating for amending them. However, on order of business items, which deal with reports and questions with low inter-institutional implications, the 2014 agreement incentivised or provided constraints for both groups to increase cooperation. Our data confirms that the EPP-S&D cooperation on these files was less frequent after the agreement fell apart in 2017.

Finally, we expect the 2014 agreement to have increased the EPP-S&D cooperation on policy issues on which the two groups have distinct ideological positions: socio-economic and socio-cultural issues (H4). By contrast, the agreement should not have affected coalitionbuilding on votes regarding the EU integration and the international affairs. In these two domains, the EPP and the S&D usually have similar positions and show strong interest in cooperating. This analysis focuses on final reports adopted through the ordinary legislative procedure. The data presented in Figure 5 supports our expectation: the EPP and S&D groups adopted together 98% of legislative socio-economic reports when the deal was in place, against 86% after it fell apart. We observe the same trend for votes on socio-cultural issues. On the contrary, the agreement did not affect coalition-building on votes related to the EU integration, and cooperation on internal affairs did not increase with the presence of the agreement. On international matters, cooperation was even higher during the period not covered by the agreement, from 2017 to 2019. This might be related to the content of specific files, but also to the pressure for the EP to adopt international agreements before the end of the legislative term.

To sum up, as expected, the agreement reduced political conflict between the two main groups on policy issues on which they usually have diverging views. However, when they have closer positions, they keep cooperating regardless of the presence of the formal political agreement.

[INSERT FIGURE 5]

Conclusion

The aim of this paper was to study the impact of a formal political coalition agreement on actual coalition-building in the EP plenary. In 2014, for the first time in the EP's history, a political agreement was signed between the EPP and the S&D -along with the ALDE -because of the Spitzenkandidaten process and as a strategy of pro-European forces to limit the legislative influence of Eurosceptic MEPs. The agreement fell apart in January 2017 in the context of the EP's mid-term internal elections. These two events provide us with the unique opportunity to better understand actual coalition-building in the EP. More specifically, this paper assessed whether and under which conditions the 2014 agreement had any effect on the level of cooperation between the EPP and S&D groups in plenary. We use a roll-call vote dataset to study coalition-building in plenary during the eighth legislative term (2014)(2015)(2016)(2017)(2018)(2019).

We find that the 2014 coalition agreement did impact actual coalition-building in the EP plenary. However, it did not affect all types of votes to the same extent. Two explanations of coalition-building in the EP plenary help understand the conditional effects of the agreement on legislative behaviour: actors' interest and ideology. We find that in cases where the EPP and the S&D have usually a strong interest to work hand in hand (on legislative reports, nonlegislative reports with high inter-institutional implications, and internal matters), the 2014 agreement did not increase inter-group cooperation. Similarly, ideology does play a role: the EPP-S&D cooperation was not affected by the agreement in policy areas where the two groups usually have similar ideological positions. In sum, when the two groups are used to cooperate, because of shared interests or policy proximity, the agreement did not affect much cooperation.

By contrast, it significantly increased it on files where the two groups usually compete the most.

Our results also prove the relevance of the historical new-institutionalist approach in the EP, which insists on path-dependency, and of sociological institutionalism. Indeed, although we find an evolution in the level of cooperation in plenary, the variations in the behaviour of political groups are limited. The technical agreements between the EPP and S&D groups, the development of negotiation routines, as well as the socialisation of MEPs to a norm of consensus allow both groups to cooperate smoothly in some activity aeras even when there is no formal agreement between them. However, the brief existence of a formal political agreement between the EPP and the S&D (between July 2014 until January 2017) has certainly contributed to reinforce all those phenomena.

In light of these results, we consider the coalition agreement signed in 2014 as a general framework that either constrained or gave incentives to legislative actors (MEPs and party groups) to increase their cooperation where they are the least likely to cooperate. With the end of this agreement in 2017, the EPP and S&D groups returned to a "normal" situation with interests and ideology determining their legislative behaviour and coalition-building strategies.

Our results show that, although the structure of competition in the EP is overly consensual [START_REF] Novak | Enduring consensus: why the EU legislative process stays the same[END_REF], it can also be politicised if legislative actors want to do so. From a political representation perspective, this process of politicisation may be beneficial: political conflict increases media coverage, fuels citizens' political interest, and better links electoral politics to policy outcomes.

The results presented in this paper need to be supplemented by other studies. First, a qualitative analysis is needed to better understand the way legislative actors considered the 2014 agreement and how it changed their day-to-day behaviour. Second, beyond plenary, we need to know more about the way the EPP-S&D cooperation was organised within committees and informal meetings, and how the end of the agreement affected negotiation routines. Third, the role of the liberal ALDE group, which was not the focus of this paper, is worth a more thorough analysis. Finally, further empirical research is needed to better understand coalition-building in the new legislative term. After the 2019 elections, the EPP and S&D groups did not negotiate a political agreement like in 2014, mainly because the Spitzenkandidaten procedure was not fully implemented. However, they have agreed on a technical agreement whose aim was to share the Presidency of the assembly throughout the legislative term. Qualitative research would help understand how the experience of the political deal between 2014 and 2017 affected the coalition strategies of the EPP and S&D groups' leaders in the aftermath of the 2019 European elections.

In our roll-call votes dataset, when the EPP and S&D voted together in plenary during the eighth term, the liberal ALDE group joined the EPP-S&D coalition in 92.9% of cases.

The wording of the written deal, reavaled in the press, is the following : 'They agree that the S&D Group will appoint the President of the European Parliament in the first half of the legislative period and the EPP Group in the second half'.

ANNEXES

Annexe I. Policy issues of reports determined by the responsible committee

Policy issue

Committee responsible for drafing the report