In many advanced democracies, mainstream political parties have been disrupted either by the rise of new (populist) parties or by hostile takeovers. In this article we argue that immigration attitudes have had a powerful impact on the strategic environment of political parties and leaders. We show, based on evidence from a comparative study conducted by YouGov in spring of 2015, that immigration attitudes had, by that time, driven a wedge between mainstream parties — those that regularly play a role in government — and their partisans. This ‘immigration gap’ opened up enormous space for new political movements to form, either inside existing parties or outside. Furthermore, we show that the representation gap on immigration issues is a relevant predictor of vote choice, so that parties are particularly likely to lose votes when they are more distant from their supporters on immigration.