This paper examines the influence of populist attitudes on party preferences conditional to the degree to which a populist party is an established player in the given party system. We do so using a two-step regression approach that allows us to investigate the varying effect of external efficacy in a multi-level setting. Making use of data on 23 EU member states, we empirically demonstrate that the support of populists, indeed, varies dependent on the question whether these parties are long-standing actors in their national parliaments and whether they have participated in national governments. This is true for Western and Eastern European populist parties. These findings make an important contribution to the broader literature on the success and survival of populist parties as they indicate that these parties do not keep up their image as radical opponents of the political establishment the more they become electorally successful and join government coalitions.
