Reassessing the Influence of Party Groups on Individual Members of the European Parliament

Abstract: This paper reassesses the way in which the voting behaviour of individual members of the European Parliament (EP) is influenced by their national and European party delegations. It does so within the previously used framework of one agent with two principals. First, it shows that the previous literature was unable to fully fathom the mechanisms through which the tripartite principal-agent relationship works. Second, it develops a model that looks solely at the votes contested between the European and the national group and the results of the test correct many of the findings of the previous literature. The paper also develops a new theoretical framework of vote cohesion in which the national and European groups are motivated by group norms and external incentives. Finally, the analysis of roll-call votes from the sixth EP finds that the new members from Central and Eastern Europe are more likely to stay with their European group than the members from Western Europe.