After Newt Gingrich’s smashing victory in South Carolina yesterday, here’s my wagering advice: You can still put your money on Mitt, but don’t bet the farm. Not this year.

The results for Mitt Romney weren’t pretty. After finishing a poor fourth in both Iowa and New Hampshire, Newt carried all but three SC counties (including Nikki Haley’s Lexington County and Jim DeMint’s Greenville County), every congressional district, and every region of the state. 

But the really bad news for Mitt is in the exit polls, which show that his support resides in precisely that narrow corner of the Republican electorate least in sync with the party’s conservative zeitgeist. Romney carried voters with postgraduate educations or incomes over $200,000; self-identified moderates and residents of core urban areas; opponents of the Tea Party and supporters of legalized abortion. And Romney’s past pattern of being a solid second-choice option for voters preferring someone else may now be in danger: Only 38% of SC voters said they would “enthusiastically” support him if he is the nominee, a number uncomfortably close to his actual 28% of the vote. 

Romney’s vote in SC was also alarmingly concentrated among voters who made up their minds in 2011. In other words, he did not campaign very well in the state, despite a lot of advantages in terms of local party endorsements and money. (For all the talk of Gingrich’s SuperPAC expenditures in the state, Mitt’s SuperPAC at a minimum matched them, and overall pro-Romney spending on television ads probably just about doubled the pro-Newt air war.)

Everything about the dynamics of the South Carolina race suggests that Gingrich’s attacks on Romney as an out-of-touch corporate pirate meshed smoothly with weaknesses Romney himself exposed, in his clumsy handling of publicity about his missing tax returns, his offshore wealth, and his vast speaking fees. Meanwhile, the success Mitt had in Iowa (with a major assist from Ron Paul) in encouraging conservative doubts about Gingrich’s commitment to The Cause was obliterated by the former Speaker’s stunning ability to get conservatives to identify criticism of his record or of his personal life with the hated partisan and ideological enemy—the media elite.   Some of this was perhaps fortuitous: Gingrich will probably never again enjoy such useful foils in televised debates as Fox News’ Juan Williams or CNN’s John King, and we are approaching another phase in the nomination contest with few scheduled candidate debates. But by luck or by design, Newt is beginning to build a Teflon shield around his stormy past, reminiscent of those old-time southern segregationists who were able to discredit questions about corruption or misgovernment by attributing them to the common enemy “up north.” Romney is not benefitting from a similar sense of partisan and ideological solidarity.

Yet even if Gingrich can continue to preempt—or as in South Carolina, exploit—criticism of his past, and can also continue to convince primary voters to ignore general election polls and imagine him vanquishing Barack Obama in debates, the landscape is about to get much more difficult. The Florida primary on January 31 offers him a chance to do some more lasting damage to Romney, and all but eliminate talk of Mitt’s “inevitability.” But it’s a very expensive state, and unless Sheldon Adelson can be talked into really loosening the purse strings, Gingrich will have no prayer of remaining competitive financially. Romney’s Restore Our Future SuperPAC has already spent $4.8 million in Florida, mostly for anti-Gingrich ads, and Mitt’s campaign has probably banked an early lead among the nearly 200,000 Floridians who have already cast absentee or early votes. Moreover, Gingrich will still have to contend with competition from Ron Paul and Rick Santorum, neither of whom are showing signs of getting out of the race (though Paul is likely to concentrate on small-turnout caucus states, and it’s hard to imagine Santorum raising the funds to compete seriously in Florida).

Will the surge Gingrich has already exhibited in national polls during the last week carry over to Florida? He better pray it does. Without an upset win in Florida, Gingrich faces a hiatus in the campaign that could prove deadly, as party elites become alarmed about the consequences of an extended contest, and the many skeletons in his closet threaten to burst into view. Newt is already looking at an almost certain loss on February 28 in Romney’s native state of Michigan, and is already in the hole for Super Tuesday on March 6, thanks to his failure to get on the ballot in Virginia.  

So it’s do-or-die for Gingrich in the Sunshine State. And for Mitt Romney, it’s time to play error-free ball before the unlikely double-rise-from-the-grave of his unlikely rival begins to convince party leaders that he’s no better than zombie bait. 

Ed Kilgore is a special correspondent for The New Republic.