Support for insider parties: The role of political trust in a longitudinal-comparative perspective

European democracies have experienced drastic changes in electoral competition. Voter support for insider parties that have traditionally governed has declined while support for radical and populist parties has increased. Simultaneously, citizens’ declining political trust has become a concern, as confidence in political institutions and actors is low across numerous countries. Interestingly, the linkage between political trust and support for insider parties has not been empirically established but deduced from the fact that outsider parties are often supported by dissatisfied citizens. We address this gap adopting both an institutional- and an actor-centered approach by investigating whether trust in parliaments and in parties is associated with the electoral performance of insider parties on the aggregate level. Combining different data sources in a novel way, we apply time-series cross-section models to a dataset containing 30 countries and 137 elections from 1998 to 2018. Our results show that when political trust is low, particularly institutional trust, insider parties receive less electoral support. Hence, we provide empirical evidence that decreasing levels of political trust are the downfall of insider parties, thereby opening a window of opportunity for challenging outsider parties.