The UMP is prepared to avail itself of its "droit d'inventaire" in regard to the Sarkozy years. Actually, the rank-and-file don't seem to be very interested: they'd rather just have Sarko back and be done with it. But the former president has lots of would-be replacements, and they're all for parsing out what he got wrong so as to claim that they, in turn, would get it right.
Jean-François Copé, the party leader, has finally hopped on this growing bandwagon, seeing an additional benefit to himself: he can remind the faithful that the Sarkozy years were in some sense the Sarkozy-Fillon years, and thus whatever Sarko got wrong should also be blamed on his "collaborator," Fillon, who just happens to be Copé's main rival. But it's a tricky game for Copé, so he is taking his precautions: he wants the "debate" to wind up quickly, and he doesn't want it to become a "personal" vendetta against Sarkozy (indeed, he needs the votes of those Sarkozy supporters who still constitute a majority of the party).
It will be interesting to tease out the subtleties when this debate actually gets under way. Everyone will of course be protesting that the UMP doesn't want to become the FN, but that's not where the real differences on the Right lie, and in any case that issue won't be sorted out by debate: it will depend on how well the FN does in future elections. If the UMP electorate continues to erode, it will be hard to keep the floodgates closed.