But Newt Gingrich may have an interesting role to play, too – as either spoiler or as distant contender for the conservative Romney alternative.
If Tuesday is the beginning of a Gingrich resurgence, it will be the third for the former House speaker. He first spiked in popularity in early December (after having been written off as a candidate by most political observers last summer) and then surged again around his unexpected win in South Carolina on Jan. 21.
Since then, however, Mr. Gingrich's numbers have sunk – and South Carolina is still the only state he's won. Rick Santorum – especially after his trio of wins in Colorado, Minnesota, and Missouri on Feb. 7 – has taken over the mantle of the conservative contender.
But Tuesday is Gingrich's big day: His home state of Georgia votes (and with 76 delegates, is the biggest prize of the night), and he looks certain to win it by a big margin. CNN has already called the state for Gingrich based on exit polls.
Moreover, he's surging in polls in some other states voting on Tuesday. He's gaining ground in Tennessee and could end up getting a number of delegates from both Tennessee and Oklahoma, even if he doesn't win either state.
Gingrich's own prediction, on Fox News on Monday, may be a bit optimistic. He told Sean Hannity, "I think we're clearly going to carry Georgia by a margin four or five times the size of Mitt Romney's margin in Michigan."
He continued, "We're surging here in Tennessee, we're surging with J.C. Watts's leadership in Oklahoma, we have a good chance to pick up some delegates in Ohio. We see some opportunities in North Dakota, Idaho, even in Massachusetts, where conservative Republicans regard Romney as a liberal governor, and there is a faction that would like to split. Not a majority, but a faction."
It's certainly possible that Gingrich could have a better-than-expected night, and he could even earn more delegates than Mr. Santorum. The nomination battle then moves into several states – Kansas, Alabama, and Mississippi – where Gingrich could have a decent shot.
All of which may still not put him on the path to the nomination. It's hard to see Gingrich, at this point, making up enough ground to topple Romney. But it could give him more justification to continue his fight (he has already vowed that he's in it until the end). And it could make him a factor in the race, primarily in hurting Santorum's chances.
Just as Gingrich is surging, Santorum is seeing much of his support sagging. He needs a good night on Tuesday to prove that his earlier victories weren't a fluke.
The candidate that may have the most to gain by a Gingrich surge: Romney.
As long as Santorum and Gingrich remain in the race, duking it out with each other for the mantle of "true conservative," Romney lacks a solid opponent. The far right's inability to coalesce around an anti-Romney candidate may end up being the boost that Romney has needed to claim the nomination, despite an apparent lack of enthusiasm.