United We Stand Still? Party Unity and Positional Accommodation on European Integration

Research on party competition typically treats parties as unitary actors, overlooking how internal disagreement may shape strategic responses to competitors. Some studies have argued that parties are more likely to accommodate their competitors when split on an issue dimension, but they rely largely on indirect measures from expert surveys. We address this limitation using over four million parliamentary speeches from six European legislatures over a 20-year period. Applying a fine-tuned multilingual XLM-RoBERTa classifier, we estimate the positions of individual Members of Parliament on European integration and aggregate these to construct a direct, speech-based measure of within-party positional dispersion. This allows us to capture party unity on European integration with high temporal and cross-national resolution. We then test whether mainstream parties’ positional responses to rising radical right support depend on their level of unity. By integrating more fine-grained measures of intra-party disagreement into models of party competition, the study contributes to a more nuanced understanding of how internal party structure shapes party competition.