Do radical right parties delay government formation? Right-wing populist and far right parties are on the rise across Europe. While established parties suffer dramatic electoral losses, right-wing parties enter one parliament after another. Recent research has studied the effect of parliamentary entry of right wing challenger parties on voter attitudes, polarization and party competition. However, despite the central importance of timely government formation for the stability and performance of political systems, we know very little about how the increasing electoral success of far right parties affects timely cabinet formation. Building on the literature on coalition formation, we argue that it is not sufficient to merely enter a parliament, but that right-wing populist and far right parties can only delay government formation when they have sufficient bargaining power. In order to test our argument, we compiled a new dataset covering 190 government formations in 22 West and East European countries from 1975 until 2019. Based on a regression discontinuity design complemented with an event history analysis, we show that the mere entry of a radical right party into parliament has no effect on government formation, but that radical right parties can significantly delay the formation of a cabinet when they are pivotal for a legislative majority. Our findings have important implications for understanding the relationship between party competition, polarization and government formation.