Socialist Threat? Radical Party Entry, Electoral Alliances, and the Introduction of Proportional Representation

A substantial body of research shows that the entry of socialist parties to the electoral arena is linked to major political and economic reforms at the beginning of the twentieth century. However, how socialist parties have affected electoral competition and coordination has never been investigated in detail. Drawing on the debate of the adoption of proportional representation, I employ a regression discontinuity design to estimate the casual effect of socialist entry to the electoral arena on the formation of electoral alliances and the support of established parties. To do so, I use newly collected data for Imperial Germany 1890–1912. I show that established parties facing strong socialist competitors received more endorsement by other non-socialist parties and, as a result, a higher voter share. The findings suggest that established parties were able to mitigate coordination problems within the institutional setting of majoritarian electoral systems.