Replication Data for: Deserting or Disengaging with Valence Populists: The Decline in 5-Star Movement Partisan Preference

Within 18 months of its second consecutive general election (March 2018) as Italy’s largest party, the valence populist 5-Star Movement (M5S) had dropped to polling 4th, halving its 30% + vote-share, behind parties of both the right and the left. In those 18-months, the party participated in two governments: one of the right and one of the centre-left. Two broad explanations for such decline are presented here: party credibility loss related to its (non)-ideological placement and penalties associated with incumbency. The former is predicted to lead those who initially supported the party to disengage from party preferences while the later is predicted to have respondents desert their preference for M5S to other parties. Using Italian panel survey data on partisan representation from March 2018 through September 2020, this manuscript identifies the opinions of those who those who deserted the party, those who disengaged from party preferences, and those who remained loyal to M5S. Descriptive analysis will first call attention to the differences between loyalists, deserters, the disengaged, and survey respondents more broadly. Multivariate analysis suggests the role of incumbency-based factors as an explanation for a decline in party support. The ideological position of the party (or being beyond left-and-right) had only a minor role. A discussion then focuses on the results of populists in power and the role of ideology in valence populism. Without an ideological core, once in power, voters punish (valence) populist party as they would any other, holding them to account for leadership and government performance.