Another very good piece of reporting, from Politico’s Jonathan Martin, adds some further context. Mr. Martin reports that a group of conservative leaders like James Dobson are thinking very explicitly about which candidate might have the best chance of toppling Mr. Romney. If Mr. Perry is among these candidates, it would make a lot of sense for him to wait out their decision…

Mr. Perry will probably not get that momentum unless there is some intervention to help him. His inertia is negative at the moment. He did not perform well in Iowa, which is geographically Midwestern but whose caucus demographics are closer to those of a Southern state.

But if there is some concerted effort to help Mr. Perry — if conservative elites rally to his defense and publicly promote the idea that he still has the best chance of stopping Mr. Romney — the rules of the game might be different, and Mr. Perry might have a chance of winning there. It may be relevant that Mr. Santorum, although reliably conservative on social issues, is a Northerner rather than a Southerner, a Catholic rather than an evangelical Protestant, and as much a policy wonk as a populist, qualities that would not traditionally play well to South Carolina’s electorate.