Talking to Voters: When and how do populist party leaders address immigration in the Dutch Tweede Kamer?

Populist party leaders have been at the forefront of political debates in the last decades. Their speech has been especially influential in opposition, not only by attracting voters but also by influencing the rhetoric of mainstream parties (Mudde, 2021). But how do these party leaders adjust their debate contributions during their time in coalition or under support agreement? Here I focus on their most important issue: immigration and look to what extent populist leaders' speech is distinctive from other party leaders in the Dutch Tweede Kamer. Theoretically, I hypothesize that both the salience and distinctiveness of speeches concerning immigration mainly serve as signals to voters and are not constrained by the legislative agenda. In the empirical analyses, I rely on the ParlSpeech corpus of Tweede Kamer speeches from 1994-2019, and – using a dictionary approach and a supervised machine learning classifier – I then measure the salience of immigration issues during agenda topics concerning immigration and during other legislative agenda items. In addition, I also measure this distinctiveness of legislative speech while explicitly removing party references. The analysis not only concentrates on between-party dynamics during the entire period but also zooms in on LPF speeches during the 2002-2003 coalition period and PVV’s speeches during the 2010-2012 legislative support agreement period. The results contribute to the literature on legislative speech in general, and on populist party leaders' political communication and coalition signalling in particular.