So even Perry is surely not dumb enough to think he can win the Republican nomination.
I should think it was the Establishment Republicans that encouraged the poor benighted Texan governor to continue with the race in South Carolina. They are desperate to split the Fox News voting block, of course. And once New Hampshire is done, Romney is in real trouble in South Carolina and Florida. So encouraging Perry to stay in the race makes sense in order to try to prevent the sense of a failed Romney candidacy emerging in the South.
Maybe Perry will split off some of the Santorum momentum - 10% might vote for a village idiot, so long as he has the proper flag pin and does a good advertisement - and I'm sure Rove will find the funds to attack Santorum using Perry as his tool. At least, that's surely the Rove/Romney hope.
They can then ditch the poor sap.