Populist radical right (PRR) parties have increasingly occupied positions of power in recent years, inspiring much scholarly interest in the mainstreaming consequences of government responsibility. This article analyses the extent and manner of mainstreaming of the Rassemblement National (RN) while in power at the local level of government in France. A municipal-level focus enables the novel inclusion of the party into the debate about the consequences of government participation for the PRR. We conduct a paired case study analysis of RN-led Hénin-Beaumont, the political base of Marine Le Pen and her ‘de-demonization’ strategy, alongside nearby Lens, which is led by a mainstream party. We analyse the policy and discourse of the administration through a qualitative content analysis of mayoral statements and data from semi-structured interviews with local politicians. The results show a partial mainstreaming due to the strategic exercise of local government power to present a more moderate and capable image, as well as the use of populist discourse to frame mainstream opposition forces and the local press as working against the interests of ‘the people’.