How do critical events reshape political discourse on multiculturalism? This study examines how terror attacks reshaped political discourse on multiculturalism in France between 2014 and 2021. By analysing 143,870 tweets from major political parties, the research investigates how far-right narratives relate to mainstream political communication. The paper is based on a novel dataset of tweets collected in the framework of the ANONYMIZED project. We track the salience and sentiment of multiculturalism-related discussions across political parties by using a XLM-RoBERTa model using Natural Language Inference to classify texts. The findings reveal significant shifts in political discourse on multiculturalism during terror attacks. We find no clear evidence of salience contagion, where critical events increase the prominence of multiculturalism in political discourse. However, we do observe heightened negative attention to the issue across parties. Following critical events, mainstream parties, particularly right-wing ones, adopted a more negative tone, aligning more closely with far-right positions. A critical mechanism identified is the “civic framing” strategy, where opposition to multiculturalism is framed as a defence of secularism and liberal democratic values by both the far right and the mainstream-right. The findings point to a trend in French politics toward accommodating illiberal discourses, extending beyond the far right. These results also deepen the understanding of how illiberal discourses gain traction in contemporary democracies, particularly during periods of heightened public tension.