This chapter deals with the creation of an online open citizen primary (primary.org) for the French presidential election in 2017 outside the traditional party system. It raises two main questions: to what extent does this procedure contribute to dematerializing the party? What are the main obstacles to this attempt at subverting the traditional party order? We argue that open primaries are one of the organisational responses to the general mistrust towards political parties. Even if they are open to non-members of the party, they are organised and controlled by party leaderships. The platform primaire.org offers online non-partisan procedures by making them truly open as far as candidacies (‘candidature’) and voters are concerned. According to our survey, based on the monitoring of the website during the election campaign and semi-directive interviews with the organisers and the designated candidate, we show that the threefold aim is to replace traditional parties in their function of selecting candidates, to offer a real alternative and to promote new political figures from outside the political establishment. Primaire.org can be analysed as a subversion device of the partisan order but one which is confronted with many problems and limits. However, the chosen candidate could not finally stand for the presidential election because she failed to get the required number of signatures from local representatives. This questions the possibility for ordinary citizens of gaining access to the presidential function. Thus, it seems that this open citizen primary was conceived as a ‘critical tool’ which denounces the functioning of classical parties, but not as a pragmatic way to seize power.