The Last Debate Before the Iowa Caucuses: What to Watch

How will Mitt Romney and Newt Gingrich approach each other the last time all the candidates share a stage?

EARLY, IOWA -- The seven major GOP candidates gather Thursday night in Sioux City for the 13th and last time before voting begins in less than three weeks. After this, the home stretch begins -- the grim final slog that will have most of the candidates frantically campaigning here through the new year. As such, the impressions left tonight could be crucial: It's the candidates' last chance to score points in a major public forum.

(While Newsmax has said it would hold another debate on Dec. 27, the fate of that gathering is up in the air now that proposed moderator Donald Trump has pulled out; several candidates also have said they will not attend it.)

A few things to watch as the sun goes down on the Hawkeye State:

1. Who's the real front-runner here? Newt Gingrich is the latest candidate to surge in the polls, both in Iowa and nationally, but there are signs he could be slipping under a barrage of attacks from his rivals. The dynamic between Gingrich and Mitt Romney has been exceedingly odd since Romney's campaign officially went on the attack last week, as Romney has seemed a reluctant warrior and Gingrich has claimed he's remaining positive even while he gets his zingers in. How they approach each other -- and who gets the upper hand -- will set the story of the campaign in its final weeks.

2. Can Gingrich keep to the high road? The former House speaker has made much of his supposed refusal to attack the rest of the field, though he's actually gotten plenty of licks in, like when, at the last debate, he said to Romney, "The only reason you didn't become a career politician is you lost to Teddy Kennedy in 1994." Gingrich has spent his whole career as a rhetorical bomb-thrower and he's got a way with a cutting remark. But at a time he's trying to prove he's not the undisciplined candidate his rivals depict, he can't afford to fly off the handle.

3. The second tier's last chance to shine. After the debate, Michele Bachmann will set out on a frantic 10-day tour of Iowa's 99 counties, an exhausting attempt to go all-in in the state. At the same time, Rick Perry will be continuing a 44-city bus tour he began this week, and Rick Santorum will continue the ongoing grass-roots effort that's taken him to more than 300 Iowa campaign events. But as these three continue to wrestle each other for the same slice of the electorate, none is likely to consolidate support unless he or she can light a fire with a breakout moment at the debate.

4. The Ron Paul wild card. Paul is generally ignored by his fellow candidates as an outlier, but he's now a real threat. The libertarian congressman has the best organization in Iowa and comes in near the top in many polls of the state. At the same time, his supporters are often seen as their own tribe, distinct from the persuadable party regulars the other candidates generally court. It will be interesting to see if any candidate sees an upside in denting Paul's luster now that he's made such inroads.

Image credit: Getty Images/Kevork Djansezian