It's a big night for Mitt Romney -- almost, I would say, either the beginning of the end or the end of the beginning.
Lots of Republicans will be watching tonight's debate carefully. If Romney cannot fend off a challenge from a manifestly flawed candidate like Gingrich, then he's toast when he comes up against the President's slick political machine.
His success or failure may determine whether South Carolina is a blip or the beginning of a long slide that spells danger for the GOP's chances next November.