This too in moderation: Evaluating the effect of delegate dissatisfaction on ambitious party group switching in the European Parliament

Abstract

The literature on party group switching in the European Parliament claims that members who are ideological outliers have the highest odds of changing their group label, but is it true that the most incongruent legislators are also the most successful at switching groups? This article seeks to determine whether or not voicing dissatisfaction by casting votes against the party line is associated with an increased probability of party group switching. Using logistic regression with a penalized maximum likelihood estimator, the analysis of ambitious switching (1979–2009) uses loyalty and policy distance variables to show that moderate, not extreme, outliers have the highest odds of exiting their group. These findings revise what we know about the relationship between legislative voting behavior and party switching, and they have important implications for examining the effect of policy-seeking on party switching in national parliaments.