National Parties and Group Membership in the European Parliament: Ideology or Pragmatism?

This paper investigates the factors behind political Group membership in the European Parliament. At the beginning of each legislative term, political Groups are formally constituted. In June 2009, more than 150 national parties, from the 27 member countries of the EU, joined one of the seven transnational groupings. Two main explanations of Group membership are advanced. A first, traditional argument for Group membership is based on the ideological or policy compatibility of the member parties within each political Group. National parties will join the political Group that best matches their programmatic position. A second argument focuses, instead, on the structure of incentives in the European Assembly, positing that the office and pragmatic goals of national parties are better advanced by joining the largest and most influential Groups. These arguments are tested by fitting a multinomial logit model for political Group 'choice' based on the 2009 Euromanifestos data. The findings suggest that ideology or policy compatibility is the most important factor behind a party transnational affiliation. A note of caution is, however, warranted for the new members of Central and Eastern Europe, whose ideological fit in the political Groups appears to be more problematic than for West European parties