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High Stakes, High Drama for Final Debate Before Voting Begins

SIOUX CITY, Iowa – It’s been 32 weeks since the first Republican presidential debate. Since then, a changing cast of contenders has faced off a dozen times across the country with millions watching at home.

Of the original combatants from that May 5 meeting in Greenville, S.C., only two, Ron Paul and Rick Santorum, remain. There have been four lead changes in national polls, two candidates drop out, four candidates join the field and billions of pixels poured out by reporters and pundits trying to make sense of it all.

Tonight, that all culminates here on the western edge of Iowa with the 13th showdown -- the last chance for candidates to make their cases before voters start the process of picking a presidential nominee. Even in a cycle that has been shaped by televised debates like no other, the stakes for the candidates this evening are enormous.

Here’s what’s on the line for the six men and one woman vying for the chance to confront Barack Obama:

Gingrich’s Perilous Perch

Like the frontrunners before him, former House Speaker Newt Gingrich has the most at stake in this debate. But Gingrich’s challenge is different from some of his predecessors’ because so much of his success can be attributed to debates themselves.

Gingrich surged to the forefront for debate performances in which he reserved his most pointed attacks for President Obama and the debate moderators themselves. The previous frontrunner, Herman Cain, also owed his stature to good debate showings, but Gingrich’s style – wry, impish lines lobbed in from the wings of the stage – isn’t suitable for a frontrunner.

Gingrich survived his first debate as the frontrunner, an ABC affair Saturday in Des Moines, by sticking to his pledge to only be negative when directly attacked. But he has now been under withering fire from his rivals for two weeks and it’s starting to take its toll. His poll numbers are starting to slip. While some settling after the meteoric rise would be expected, Gingrich has only been the frontrunner for about three weeks, and his support is far from solid.

While Republicans may not be so keen on Mitt Romney, the formerly media-averse former Massachusetts governor has taken to the airwaves with gusto to deliver repeated attacks on his rival. Meantime, Ron Paul and Texas Gov. Rick Perry have joined in with commercials and media appearances. The message from all three is that Gingrich is an inconsistent conservative and a creature of the Washington establishment.

If Gingrich stays on his course of only parrying his rivals attacks he will spend an awful lot of time on the defensive tonight. Gingrich wants to talk about solutions and big ideas, but his opponents want to talk about only one thing: the former speaker’s extremely complicated record as a Republican icon.

His no-first-punches doctrine puts Gingrich in a bind when the topic of conversation in Republican America is all about his record.

The End of Mittness Protection

Mitt Romney looked wise for staying out of the spotlight for most of the cycle so far. But his semi-stealth campaign is now looking less savvy.

Romney relied on his big war chest and strong support among the quarter of moderate Republicans looking for an alternative to Barack Obama that would seem like a steady, sober choice to undecided independents in the general election.

While he was raising money in New York, L.A. and London and holding chicken chili luncheons in New Hampshire, Romney’s rivals trampled each other as they tried to squeeze into the media spotlight. Romney looked more presidential and developed an ever-greater aura of inevitability.

But the problem is that Romney missed his chance to try to re-introduce himself to conservatives on their terms. Always skeptical of his red-state credentials, Republicans have hardened in their negative attitudes about Romney.

Now, Romney is on a media blitz trying to ruin Newt Gingrich’s chances. Romney swatted at Rick Perry before, but Perry mostly sunk himself with bad debate performances. The anti-Gingrich campaign is nastier and more sustained than anything before.

Romney has little choice since Gingrich, the best known and most moderate of the conservative contenders in the “not Romney” intra-primary, poses an existential threat to Romney’s strategy of picking up wins on friendly turf and delegates everywhere else with a lot of second-place finishes.

But having been the submariner candidate before (“run silent, run deep”) now means Romney is using his media spotlight moment to do something voters hate: ceaselessly attack a fellow Republican.

Romney bets he can fall back on his reliable core of support to rebound in New Hampshire and regain his footing. But waiting for him in the Granite State is former Utah Gov. Jon Huntsman, a fellow Mormon and a fellow moderate, who has staked his entire strategy on New Hampshire. With Gingrich pulling in some support there and Huntsman gaining ground, Romney faces additional peril with his scorched-earth campaign.

Huntsman always gets under Romney’s skin, and tonight watch for the former ambassador to China to have his longest needles out for his New Hampshire rival.

Driving up his own negatives with the rough stuff may be necessary to knock down Gingrich, but Romney may not have the cushion he once thought he did. The one time frontrunner avoided the early perils of a high-visibility campaign in a boom-and-bust cycle, but he has left himself with a tough task in the closing debate.

Can he derail Gingrich without running off the track himself?

Plausibility Test for Paul

Republicans love Ron Paul on domestic issues, but can’t abide his foreign policy. His task tonight is to either allay those concerns or at least not exacerbate the problem.

Paul is staging a rally in Iowa based on the best grassroots organization and conservative frustrations with Romney and Gingrich. A good showing tonight means looking like a plausible choice to Iowans who don’t want to look foolish with their caucus pick.

Paul doesn’t have to look like the nominee, but just like someone fed up Iowa Republicans wouldn’t be embarrassed by later on.

In this year’s first debate, Paul was greatly advantaged by the killing of Osama bin Laden by a team of U.S. commandos less than a week before. It buttressed his argument that it was time for America to leave Afghanistan and focus on getting the federal government under control.

The latest news is less helpful. Many Republicans have grave misgivings about the fact that today marks the official end of the U.S. military presence in Iraq. While some may be sorry about the way the war was handled or that it was even begun, most Republicans believe that the Middle East is going the wrong way for the United States very rapidly.

Iran is on the rise, American allies are under siege and Russia and China are goading their friends in Tehran to make it even worse. With so much angst, Paul’s policy of immediate disengagement and rapprochement with Iran will not sound so good to skeptical Republican voters.

Paul’s task is to not say more than necessary on the subject and keep the conversation where he can benefit most: a test of the candidates’ conservative consistency.

If Paul looks too risky on foreign policy, Iowans have other options among the conservative alternatives. Rick Santorum and Michele Bachmann have thrown themselves at the feet of Iowa conservatives begging for the chance to be their champion.

Most dangerous for Paul, though, is his fellow Texan, Perry.

Perry’s boom and bust occurred when conservatives were still dreaming of perfection. Now, having endured Herman Cain’s embarrassing collapse and been forced to rationalize their way through Gingrich’s apostasies from a 40-year career in politics, Perry’s main weakness, poor debating, looks less glaring.

Perry is using his cash reserves to push hard on his status as an evangelical Christian and his stature as the governor of a very large, very Republican state. If Paul fails the plausibility test, the folks out here in cattle country may opt to saddle up again with Perry.

Chris Stirewalt is digital politics editor for Fox News, and his POWER PLAY column appears Monday-Friday on FoxNews.com.