The recent emergence of right-wing populists proved to be a tremendous challenge for political systems across Western Europe. This should also apply to legislative institutions. Growing polarization between parliamentary party groups and ignorance towards representative democracy are likely to be accompanied by a more aggressive tone, also among established parties. Furthermore, challenger parties should moderate once they enter parliament, as they are included not only in public speech, but also legislative processes and parliamentary committees.

There is little systematic research on how right-wing populists have affected debates, processes, and norms within legislatures. This contribution presents a new corpus of more than 900,000 speeches held in 16 German state parliaments over 30 years that allows comparative analysis inside the same political system. We measure the incivility of political discourse using dictionary-based sentiment analysis, measuring the changes in tone over time. To capture populism, we develop and validate a dictionary for populist speech using word embeddings.

We find that right-wing populists approach parliamentary discourse as expected. They communicate more populist and negative – which, however, does not affect other parties’ behaviour significantly. Instead, we observe a generally positive trend in sentiment. Interestingly, tone seems to be mainly determined by the opposition-government cleavage.