Caught Between the Poles: Mainstream Parties in Multi-Polar Competition Over the Immigration Issue

A large body of literature focuses on the restructuring of the political space in postindustrial Western Europe. While many contributions study the causes and effects of niche party success for mainstream party repositioning on new salient conflict dimensions, we still know little about how mainstream party repositioning affects the compositions of their own electorates. In this contribution, we analyze the effects of mainstream party repositioning on the increasingly salient issue of immigration on the voters they keep, win, and lose. We argue that changes in mainstream parties’ immigration platforms alert voters to the issue and to the parties that are most outspoken about the issue – left libertarian and radical right parties, which occupy opposite poles on this issue dimension. Consequently, we expect that mainstream party shifts catalyze bidirectional voter transfers between mainstream and niche parties and show that mainstream parties alienate more voters than they win (back) by going tough on immigration. We thereby establish that the increase in voter migration between mainstream and niche parties in response to mainstream party policy shifts constitutes an important mechanism for explaining the consolidation of radical right and green parties in West European party systems.