Fred Thompson is dropping out. Marc Ambinder offers a Thompson campaign retrospective. He says “in many ways, he tried to occupy a space that John McCain more credibly occupied; national security strength, straight talk on the economic challenges facing the country and resiliency.” Maybe. Certainly I’d assume that Thompson, who’s pals with McCain, hopes that’s right and his pool of supporters drifts that way. But in most regards I’d say Thompson tried to occupy a space that Mitt Romney less credibly but more effectively occupied — plain-vanilla conservative.