Palin.
As an aside, I believe Mittens would have locked up the nomination months ago had he done a mea culpa on Romneycare instead of trying to rationalize it. Any attempt to move away from it now would be seen as just another flip-flop. At least Newt's done the mea culpas about his couch session with Pelosi and some other things, and he's proven his conservative bona fides back in the '90s during his term as Speaker.