The article examines the response of the French National Rally (Rassemblement National – RN) to COVID-19. It combines computer-based and qualitative content analysis of Facebook posts and press releases to uncover the salience and frames of the infection. I find that the RN used an ambivalent strategy to respond to the pandemic, linking an unexpected problem to its core ideological tenets, while also adapting its programmatic profile. Specifically, the RN interpreted COVID-19 in terms of immigration and defence. Diagnostic frames drew on nativist, authoritarian and populist tenets to identify the origin of the infection (migrants), and to attribute blame for its spread (lack of border controls). Moreover, prognostic frames used disagreement within the scientific community to criticize governments' policies and propose alternatives. While this strategy allowed the RN to address an issue outside its ‘comfort zone’, its support base remained stable. These results point at the radical right's strategic use of expert knowledge and populist logics to try to improve its credibility in mainstream public debates.