It’s the last debate before Super Tuesday and perhaps the last debate of the 2012 GOP presidential race.

And there’s a lot at stake. A whole lot.

Republican presidential candidates (L-R) former House speaker Newt Gingrich, former senator Rick Santorum and former Massachusetts governor Mitt Romney greet each other at the start of a debate sponsored by CNN at the University North Florida on Jan. 26, 2012 in Jacksonville, Florida. Tonight’s debate is the first since then. (Photo by Joe Raedle/Getty Images)

For now, though, here are some storylines to watch:

* Rick Santorum, center stage

Santorum emerged as a frontrunner more than two weeks ago. This is the first debate since then, which means that, for the first time in this entire presidential race, Santorum will no longer be a bit player on the debate stage.

With that distinction, though, comes all kinds of challenges. In recent days, Santorum’s past statements have become a major issue, and we’re sure he’ll have to answer for many of them tonight.

The former Pennsylvania senator has shown himself to be a very capable debater – even if he’s a little too angry-man at times. But it’s much easier to come off well when you’re at 5 percent in the polls and aren’t being attacked. Tonight will be much, much different.

* Newt Gingrich’s last hurrah?

The former House speaker has basically nothing except for Sheldon Adelson going for him right now. And tonight’s debate might well be his last good chance to change that.

Gingrich made a name for himself in the presidential race with his debate performances, but then he fell off the map with a pair of clunkers before the Florida primary. There haven’t been any debates since then, and Gingrich has struggled because of it. And with next week’s Georgia debate being called off, Gingrich won’t be able to count on that for momentum pre-Super Tuesday.

Gingrich needs a moment reminiscent of his exchange at the Myrtle Beach debate with Fox News’s Juan Williams. Look for him to come out swinging like a prize fighter who needs a knockout in the 12th round – or else he loses.

* Social issues

These were an afterthought in previous debates; in fact, at one point, ABC’s George Stephanopoulos drew puzzled looks for asking about contraception in New Hampshire. Now, though, contraception is the issue du jour, and everyone wants to talk about social issues.

Except, that is, for the candidates. But it will be hard to ignore these issues – particularly since gay marriage has passed in a few states in recent weeks and there’s an ongoing debate over “personhood” and pre-abortion ultrasounds in Virginia, which has colored Gov. Bob McDonnell’s potential vice presidential hopes.

It’s hard to see how this isn’t a big part of tonight’s debate. The question is whether that hurts or helps Santorum, who is a social conservative’s social conservative but has also marginalized himself on certain issues.

* Does Mitt Romney play it safe?

The former top dog’s economic plan today suggests a guy who is refining his message and trying different things. But is it really panic time?

Maybe that was the case Tuesday, when a new CNN/Time poll showed his lead in Arizona’s primary was in jeopardy, in addition to his problems in Michigan. But today, new polling from NBC News and Marist College suggests he’s recovered a bit, and as long as he thinks he can keep that going over the next week, maybe he plays it safe tonight.

If anything, look for him to call into question Santorum’s conservatism on abortion and government spending. If he can undermine Santorum’s credentials on those issues and cast doubt on the former Pennsylvania senator’s status as a conservative hero, Romney will have had a good night.