In this paper, we examine the phenomenon of use of sovereignist claims, not only by nationalist or populist leaders but also by actors who would not normally fall into these categories. We zoom in on two different cases, France and Italy. Through an analysis of Twitter, a platform used by political leaders to communicate their desired messages to the public like an un-mediated press release, we examine the discourse of the political leadership in election campaigns. We document some interesting commonalities, as well as some important differences, concerning the penetration of sovereignist claims in these two countries. We produce an account of the patterns of politicisation of sovereignist issues, we identify which parties/leaders have been the main entrepreneurs of sovereignist claims and how their competitors have responded to this challenge. Finally, we analyse the main drivers of sovereignist party discourses. Through multivariate regression analysis we show how, both in France and in Italy, the sovereignist supply has been influenced by ideology and voters’ demands, a finding that has important implications for the cleavage structure of the political system in these two countries.