Rebel Rebel. Do Primary Elections Affect Legislators’ Behaviour? Insights from Italy

MPs elected in 2013 Italian parliamentary elections have been selected through three main procedures: open primaries, closed primaries and exclusive methods, meaning that they have been appointed directly by the party elites or party leaders. This peculiar layout of the Italian Parliament offers the opportunity to analyse the impact on the parliamentary behaviour of different selection methods within the same political context. Drawing from a large and original data set including parliamentary behaviour of all the Italian MPs elected in 2013 parliamentary elections, this article addresses the impact of candidate selection methods by focusing on the dimension of party unity. Our hypothesis is that inclusive procedures for selecting candidates may entail a low party unity degree, namely a higher MPs’ propensity to rebellion from party line. The analysis shows that the selection methods affect only marginally MPs’ parliamentary behaviour and not always in the expected direction.