This article examines how institutional context factors influence political actors' opportunities to express their voice. For the empirical evaluation we draw on three decades of abortion debate in Switzerland, Germany and the US. We show that institutionally conditioned power differentials considerably determine the media standing of political actors. This puts particulary emerging civil society actors, such as social movements, at a disadvantage. For the Swiss case, however, we argue that direct democratic procedures countervail this effect, as they allow outsiders to make their mark in the public debate. Moreover, we find that the political parties, which are known to have a rather weak position in the Swiss institutional framework, also benefit from this. With our article we wish to support the call for a contextualisation of political communication research in terms of an "institutional turn" and to highlight the potential of comparative studies in this field.