Different signals, same message? Evidence of mainstream accommodation of the radical right on European integration using parliamentary speeches

What drives mainstream parties’ reactions to the success of the radical right? Existing research shows that mainstream parties respond by moving closer to the radical right but most studies focus on long-term adjustments based on past election results, overlooking shifts within electoral cycles and not distinguishing between different sources of information on which mainstream parties might rely. We argue that the type of electoral signal (actual vote share versus projected success in opinion polls) as well as its credibility as an indicator of challenger strength (whether the radical right is represented in parliament) is crucial. Drawing on ParlSpeech data, we analyse plenary speeches from seven legislatures over a 20-year period and measure party positions on the EU at the quarter-year level with two fine-tuned multilingual classifiers based on XLM-RoBERTa. We find that mainstream parties adopt more Eurosceptic stances in reaction to increases in support for the radical right, both when measured as share of the vote in the previous elections and as the share of the vote as predicted by opinion polls. This is only the case when the radical right is represented in parliament. However, we find no evidence that mainstream accommodation intensifies as elections draw nearer.