The designer of the French presidency intended it as a supra-partisan office. Yet this ambition was thwarted by the institutional requirement for a majority in the National Assembly, in order to pass legislation. Today, parties control the presidential function, acting as gatekeepers and enablers; their role has not been usurped by media-promoted personalities. But the presidency has its own dynamic effects on party structures, beyond the mere obligation to produce a plausible candidate. A presidential campaign is the high point of party activity, and the 2007 exercise showed a wide range of effects, according to whether parties are viable candidates for government or pure protesters, or whether they fit uneasily between these positions. This article explores some of these dynamic effects.