Shaping Parliamentary Debate: The Centrality of Party Leaders in Populist Discourse

The "inclusion-moderation" thesis posits that the involvement of right-wing populist parties in government coalitions leads to toned-down issue positions and populist rhetoric. Focusing on the speech actors, this article suggests that party leaders, not parties, are the primary drivers of populist rhetoric in legislative speech. Building on the party leader and party competition literature, it develops two specific expectations: fluctuations in populism are 1) leader-driven and 2) influenced by the emphasis on immigration in speech. Using parliamentary speech data from the Netherlands (2002-2019) and Austria (1999-2019), this study employs a large language model to measure populist speech and BERTopic models to assess immigration content. The results support that party leaders' debate contributions show higher levels of populism. Additionally, both party leaders and MPs dial back their populist rhetoric while in a coalition but intensify it when discussing their 'owned issue', immigration. The latter tendency is especially pronounced for party leaders.