Rasmussen has Romney 3 points ahead of Santorum 27-24 while the CNN poll has Mitt with a much bigger lead - 37-19 over the former Pennsylvania senator.

Gingrich is in third place in both polls with 18% in both the Rasmussen and CNN surveys.

The discrepancy may be due to the fact that Rasmussen completed his survey in a single day - January 5 - while the CNN survey was taken over January 4-5. Can't find the breakdown by day with the CNN poll but it could be that Santorum is surging dramatically on a day to day basis. That was the case in Iowa for Santorum and might explain why he is so much closer in the Rasmussen survey.

From Rasmussen:

The latest Rasmussen Reports telephone survey in the Palmetto State finds former Massachusetts Governor Mitt Romney still in the lead, earning 27% support from likely GOP Primary Voters, up from 23% in early November. Former House Speaker Newt Gingrich is in third with 18% of the vote, followed by Texas Congressman Ron Paul at 11%.

Bringing up the rear are Texas Governor Rick Perry with five percent (5%) and former Utah Governor Jon Huntsman at two percent (2%). Another two percent (2%) of these likely primary voters like some other candidate, and 11% remain undecided. (To see survey question wording, click here.)

In the first Rasmussen Reports survey of the South Carolina Republican Primary race in November, Georgia businessman Herman Cain came in first with 33% support, followed by Romney and Gingrich. Cain has since dropped out of the race.

The latest findings from South Carolina parallel the voting sentiments of Republicans nationally following the Iowa caucuses, with Romney out front with 29% support. Santorum, after his photo finish with Romney in Tuesday's caucuses, runs second at 21%, with Gingrich in third with 16% of the vote. The January 21 primary in South Carolina is especially critical for Santorum who has largely written off next Tuesday's first-in-the-nation New Hampshire Primary and is counting on the conservative, evangelical vote in the southern state to build the momentum for his candidacy.

Things remain fluid in South Carolina, however, with nearly half the state's primary voters (48%) saying they still could change their minds. Just 41% are certain already of how they will vote. Those certain of their vote include 62% of Paul's supporters, 51% of Perry's backers, 50% of Romney voters. Just 43% of Santorum voters and 36% of Gingrich supporters are locked in at this point.

One wonders what a big win in NH will do for Romney. He's beginning to look like a winner to a lot of Republicans and like it or not, almost everyone likes a bandwagon. Doubling his support in a very conservative state like South Carolina would seem to indicate something else at work besides agreement with his politics.

But Santorum is far from through. He's raising a million dollars a day and is prepared to make a huge ad buy in SC. He will have the momentum coming out of Iowa since he won't compete seriously in NH. And the state sets up far better for him than Romney demographically.

It will likely be another nail biter.