Shifting parties, rational switchers: Are voters responding to ideological shifts by political parties?

According to spatial theories of voting, voters choose parties that are ideologically close to themselves. A rich literature confirms the presence of a close connection between the positions of voters and parties, but findings from cross-sectional analyses of spatial voting might be driven by endogeneity biases. We argue that for investigating the impact of ideological distance on the vote, spatial theories of voting should be tested dynamically. Taking a Downsian perspective on voting behaviour, we assume that changes in parties' ideological positions should cause voters to switch parties from one election to another. In doing so, we also contribute to work on responsiveness to political parties. For testing the role of spatial voting dynamically, we make use of election panel surveys in four established democracies: Germany, the Netherlands, New Zealand and Sweden. The results presented in this article suggest that parties' ideological shifts may indeed cause voters to switch parties, in particular when the party closest to them changes positions, but that the overall impact remains limited.