Jon Huntsman betrayed South Carolina's largest newspaper, The State, by getting out of the race, but did everyone else a big favor. Getting the field down to five candidates was an improvement.
Rick Perry came through with one of his best outings. He gave South Carolinians a strong performance which could spur voters to provide him the support to carry on. He was terrific on federalism, provocative on foreign aid ("take 'em to zero and then have the conversation"), and said Congress (which polls miserably) should be a part-time body. All in all, Perry sounded like a nearly perfect conservative populist. It was a crime that he didn't get a crack at the gun control question. That would have been his chance to play Newt. Whether or not Perry is able to compete, he did himself and his supporters a favor with this showing. This was not a guy who has lost interest or checked out.
Mitt Romney continues to look like someone ready to be president. He has worked out the answers he wants to give and doesn't let others intimidate him. The rare missteps for him are when he is pressed on an issue he hasn't thought about much (like whether felons can vote). Romney is a control guy and does not want to think about something in front of a few million people. We should probably credit him for that instinct. He benefits when his foes compete well. They all did and will continue to divide support.
Newt Gingrich showed the same killer instinct on stage that brought him into contention in the first place. Juan Williams tangled with him and just made Gingrich look better. You smack Gingrich in the mouth and he just smiles. His basic problem is Rick Santorum. Neither of them seem ready to blink and bail out. Romney will laugh all the way to the nomination.
Rick Santorum performed well and clearly belongs in the mix. Nevertheless, he didn't help himself trying to make Romney look bad on whether or not to let felons vote. You don't pick up any GOP primary voters by showing your opponent may be tougher on crime than you are. His best moment was when he talked about the simple habits of work, marriage, and child-bearing that reliably keep people out of poverty.
Ron Paul has the wrong instincts for expanding his base (at least in a primary). The things that seem to really get him passionate in these debates have to do with the left-wing parts of libertarianism such as pacifism, respect for international law, and drug policy. If he wants to push beyond his base of support, he has to emphasize his fiscal program more effectively.