Does switching pay off? Analyzing the impact of parliamentary party instability on individual electoral performance

Party systems in modern democracies are becoming increasingly unstable. Levels of instability have been increasing in most long-standing Western democracies while most of the younger party systems in Central and Eastern Europe show limited signs of consolidation. This instability can be primarily electoral – with voters changing their preferences between existing parties or from existing parties to new contenders. However, these changes are often triggered by changed allegiances of members of parliament (MPs) during an electoral term who can: (a) exit their original parliamentary party group (PPG) and become independent, (b) defect, by joining another PPG or (c) create a new PPG (as a rule collectively with other switchers). A variety of factors can motivate MPs to change their PPG affiliation. The desire to improve their electoral prospects is often implicitly or explicitly mentioned as one of the most important among them. However, does the switching of PPG affiliation actually improve the electoral prospects of the MPs involved or does it, on the contrary, damage them?   We study the subsequent electoral performance of MPs involved in parliamentary party instability since the mid-1990s in three countries (Estonia, Lithuania, Poland and Romania) using an original dataset on all instances of parliamentary party instability compiled by the INSTAPARTY (Party Instability in Parliaments) project. The countries vary in terms of overall levels of parliamentary party instability – ranging from low and decreasing in Estonia to persistently very high in Poland. The countries also vary in terms of their electoral institutions which allows us to keep constant this factor that has been shown to impact MPs’ switching behaviour. In addition to examining MPs’ return to parliament, we zoom in on their electoral performance. We do that by examining changes in their electoral list placement compared to the pre-switching election (in other words, electoral vulnerability) and changes in the number of preference votes received. In terms of parliamentary party instability events, we go beyond the simple contrast between switchers and non-switchers and consider the electoral dividends of different types of switching – collective versus individual, defection to another PPG versus becoming an independent MP, and more complex kinds of parliamentary party instability, including the creation of new PPGs. We expect that individual switching carries smaller rewards than collective (coordinated) switching, especially if the switcher ‘exits’ their original PPG but fails to join another (existing or new) PPG swiftly. Those involved in new formations do better than those turning to existing parties as the latter may suffer from a negative “party hopping” image. When ‘defecting’ (i.e., joining existing formations), switchers often have a weaker negotiation position vis-à-vis established political parties. This is due to established hierarchies within the parties as well as possible internal resistance to the promotion of newcomers who may increase the electoral vulnerability of existing cadres. The findings of the paper advance our understanding of utility calculations behind party switching and inform practitioners devising parliamentary and electoral rules to prevent excessive party instability and forms of party switching detrimental to MPs and their constituents.