Could Rick Santorum put Newt Gingrich in the rearview mirror Tuesday?

Tuesday night is shaping up to be a good night for Rick Santorum.

While polling has been limited in the three states holding contests Tuesday (Colorado, Minnesota, and Missouri), and an unusually high number of voters are uncommitted, pollsters are predicting that Mr. Santorum will win two out of the three and should place a close second to Mitt Romney in Colorado.

The question is: Will that be enough to revive Santorum's candidacy or even put him on a path to nomination?

Despite winning (barely) Iowa's caucuses a month ago, Santorum has been largely an also-ran in the early contests, barely getting mentioned by headlines more interested in Romney, Newt Gingrich, and Ron Paul.

So why is the former Pennsylvania senator surging now?

Likeability might be one factor. According to a recent Public Policy Polling report, responsible for the most up-to-date polls in the three states voting today, Santorum has a favorability rating over 70 percent in all three states. That's in marked contrast to Romney (with favorability ranging from 47 to 60 percent) and Mr. Gingrich (47 to 48 percent).

Santorum's biggest appeal, according to PPP, is with tea partyers, Evangelicals, and voters who describe themselves as "very conservative" – all groups who had been leaning toward Gingrich, but now seem to be abandoning him for Santorum.

There are positive signs in other polls as well. While Santorum still trails both Romney and Gingrich in national polls, Gallup's daily tracking poll now has him only six points behind Gingrich, who is falling. And a new Rasmussen poll that tracks how all four candidates do in potential matchups against President Obama has Santorum as the only candidate who comes out ahead, 45 percent to 44 percent (a finding Santorum's campaign has highlighted as much as they can).

Another reason for Santorum's resurgence may be Gingrich's descent. More conservative voters seem to be getting over their Gingrich crush and, still unhappy with Romney as a nominee, are moving to Santorum. Gingrich's decision not to make any campaign appearances in Minnesota this past week – one of the few states where he might have had a chance – only helps Santorum.

(In Missouri, whose nonbinding primary Tuesday has been likened to a "beauty contest" before the actual delegate-choosing caucuses in a month, Gingrich isn't even on the ballot – another point in Santorum's favor.)

But before anyone starts speculating about the possibility of a real battle between Santorum and Romney, there are some big caveats.

For one thing, the contests Tuesday are relatively small ones – only getting attention in the February desert of the GOP primary season – and don't even mean much for delegate counts. Colorado and Minnesota's caucuses are nonbinding, with delegates actually selected when the state party holds conventions later in March or April.

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