Replication Data for: Challenging the Challengers? Quasi-Experimental Evidence on the Impact of the Bündnis Sahra Wagenknecht on German Party Competition

This article examines the transformative impact of a challenger's entry into party competition, using a quasi-experimental design to provide an evidence-based evaluation of its effects on voter mobilization, competition with mainstream parties, and interactions with other challengers. Leveraging variation in the participation of the newly formed Bündnis Sahra Wagenknecht (BSW), we analyze local elections in five German states. To account for strategic factors influencing BSW’s participation, we apply covariate balancing propensity scores to ensure comparability between treated and non-treated municipalities, enabling an unbiased estimation of the average treatment effect of BSW’s participation on changes in voter turnout and party vote shares. Except for the right-wing Alternative für Deutschland, our findings reveal a significant reduction in vote shares for all parties, with no evidence of increased voter mobilization. These results have important implications for party competition dynamics and the functioning of representative democracy in the presence of multiple challengers.