This paper aims at critically look at platformisation of digital campaigning in France, in its relationship with the transformation of the public sphere. The idea of platform politics has different meanings (Lioy, Esteve del Valle et Gottlieb, 2019), either based on the political usage of social media platforms, or the introduction of political intermediaries into the structure of political parties in order to push activists to political action. However, the relationship of platform politics with the changes in the public spheres remain unexplored. This paper looks at a specific aspect of this "platformisation" of politics, both through "platform parties" (Gerbaudo, 2019) such as La France insoumise and la République en Marche and non-platform parties (Socialist Party, The Republicains). Specifically, it monitors the strategies used by political campaigners to recruit digital affiliates and push them to action with and on social media platforms, in the context of the French presidential election, especially in order to (try) to influence the online debates. The aim of this qualitative survey research is to monitor to what extent the digital campaigning strategies rely on public spheres as such, or rather on an hybrid media system (Chadwick, 2013). It is based on about 40 interviews with digital campaigns and digital activists, as well as an analysis of presidential campaign platforms.