Political rhetoric has important effects on the quality of democracy, but we know very little about what causes variation in the tone of the political debate. We investigate how radical-right success affects the way the remaining politicians discuss political issues. Using an original dictionary, we measure different positive and negative emotions in a newly collected dataset of speeches in German state parliaments. Taking advantage of variation in the timing of elections when radical-right politicians enter these parliaments, we find that politicians of other parties respond to radical-right success by using more positive, instead of negative, emotions. A mix of quantitative and qualitative analyses suggest that the increase in positive emotions is used strategically for politicians to distance themselves from radical-right discourse. Our findings highlight how radical-right success can create incentives for other politicians to enforce norms that radical-right politicians breach.