Nate Silver at 538, which is affiliated with the New York Times, has predicted that Newt Gingrich will come in first place in the South Carolina, followed closely by Romney, followed distantly by Ron Paul, with Rick Santorum in a distant fourth (and last) place.
Silver is very data based, so his results are no doubt based on surveys and other solid data.
If he's right, there is a good chance that Santorum would drop out of the race before Florida's primary on January 31, and that Gingrich could consolidate the conservative vote at that point if it is not too late for GOP conservatives to unite around one not Romney candidate. Still, if Santorum and Gingrich combined are only predicted to win half the primary vote in conservative South Carolina, a Gingrich win is going to be a long shot.
Seth at Enik Rising has noted that the three superdelegates who had committed to Perry have been released, one defecting to Romney despite Perry's endorsement of Gingrich in an attempt to consolidate the conservative vote, and the other two not taking sides. This leaves the superdelegate count at 13 for Romney and 1 for Santorum (whose candidacy does not look like it will last past this weekend). Gingrich doesn't have any superdelegates supporting him and neither does Ron Paul. In a close race, that could be decisive, although the vast majority of superdelegates are uncommitted at this point.
UPDATE: Seth's source now says that Romney has 15 superdelegates and that Gingrich has 1, but cites an AP story that claims that Paul and Santorum each have one superdelegate and that Gingrich has two. Still each of them is in a worse position, supedelegate wise, than Perry was before he dropped out.
Gingrich is also far, far behind Romney in campaign fundraising and did very poorly in Iowa and New Hampshire. A first place finish in South Carolina by a mere three percentage points or so, would keep Gingrich's campaign alive, but by itself, it doesn't displace his strong negatives and the fact that his campaign has already come close to collapse twice during this campaign.
Gingrich hasn't necessarily given himself much credibility with the anti-plutocrat populist wing of his party by admitting to a 31% tax rate in disclosed tax returns on a $3 million income.
At any rate, a Gingrich nominee would clearly be weaker than Romney in the general election, so any improvement in the likelihood that Gingrich will be the nominee improves Obama's chances in November.