Next stop South Carolina: Can Romney's train keep chugging ahead?

If the trend so far in the primaries has been for Republican voters to vote for Mitt Romney with their heads and not with their hearts, some in conservative South Carolina are saying: 'Not so fast.' Most evangelical leaders meeting in Texas Saturday voted to back Rick Santorum.

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Also weighing in Romney's favor is the support of key figures in the state's GOP establishment, namely Gov. Nikki Haley and Treasurer Curtis Loftis. Tea partyers, who backed Governor Haley's rise to power a year ago, are upset that she has gone with Romney. For Romney, Haley provided a key endorsement in an early-voting state (the first Southern primary, no less), enhancing the air of inevitability he is cultivating.

How will Bain controversy play?

Most intriguing, though, is how attacks on Romney's record as a venture capitalist at Bain Capital will play in South Carolina, where unemployment stands near 10 percent, higher than the national average. Former House Speaker Newt Gingrich and Texas Gov. Rick Perry have gone after Romney over Bain, and an outside group backing Mr. Gingrich is spending millions on ads promoting a half-hour documentary that savages Romney over Bain's closing of businesses.

Romney is fighting back with an ad of his own that defends his record, saying he invested in businesses and helped create jobs. The Bain attack has shocked Republicans who argue that it is helping make Obama's argument for him, should he face Romney in November. South Carolina may well be Governor Perry's last stand in the campaign, and his populist attacks on Romney – calling him a "vulture capitalist" – cost him a prominent business supporter in South Carolina. Perry has since backed off.

Gingrich, too, is fighting to keep his campaign aloft, after attack ads by a pro-Romney group brought the former speaker low in Iowa. If nothing else, Gingrich has appeared to be on a revenge mission against Romney.

Congressman Paul, who posted strong numbers in both Iowa and New Hampshire, faces tougher sailing in South Carolina and Florida, where his libertarian message is a tougher sell amid difficult economic times. In short, analysts say, when times are tough, people look to government for jobs and assistance.

If Paul is harmed by the perception that he can't beat Obama, the electability argument could help push Romney over the top in South Carolina – even among evangelicals and tea party sympathizers who might otherwise view him skeptically.

If Romney manages to win South Carolina, even with a McCain-level plurality, the rest of the field will face a strong perception that the Republican race has effectively been decided, despite the fact that barely any convention delegates will have been awarded.

"If Romney goes 3-0, I think it's all over," says Jim Guth, a political scientist at Furman University in Greenville, S.C.

And even if Romney doesn't win South Carolina, he's in strong position to win the next primary, Florida. Romney is uniquely positioned with the money and organization required to win in an expensive state with 10 media markets. Florida Republicans vote on Jan. 31.

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