Perfect Timing: Leveraging the Timing of Defection to Assess the Effect of Electoral Rules on Party Switching

When legislators switch parties between elections this may be viewed as undemocratic since, bypassing voters, they are changing the outcomes of elections. Do electoral institutions affect the likelihood of party switching? I argue that legislators are less likely to switch in candidate-centered electoral systems where, because of personal voting, parties cannot insulate defectors from voter retribution. When they switch though, legislators do so early in the term to exploit voters' short retrospective time horizon. These expectations are tested using a quasi experimental research design that estimates the effect of the 2008 Romanian electoral reform on party switching. In 2008 Romania changed its electoral system from a closed-list PR to a candidate-centered electoral system, where all candidates compete in single-member districts. Both hypotheses are supported by empirics. This helps weed out competing explanations which now have to account for both the decrease in and the different timing of party switching.