By MICHAEL FALCONE ( @michaelpfalcone ) and AMY WALTER ( @amyewalter )

MANCHESTER, N.H. - It may be the middle of winter, but get ready for some heat.

Fresh off a close win in Iowa and a decisive one in New Hampshire, Mitt Romney heads to South Carolina today where he is likely to spend the next 10 days fending off attacks from several of his opponents who see the Palmetto State as their last stand.

And no one is going to try to bring the pain upon Romney more than Newt Gingrich who told ABC's Jonathan Karl this week that South Carolina is his "must-win state."

Gingrich is readying a speech, to be delivered this morning at an event in Rock Hill, S.C., that one of his aides said will be the "defining moment in the campaign."

"We're going to see the single most authentic candidate, who has run for president, who is not worried about what the consequences will be," Gingrich spokesman R.C. Hammond told reporters traveling on the former House Speaker's plane from New Hampshire to South Carolina. "He is going to put forth the truth as people see it in their lives every day."

And when all of the candidates land in South Carolina today, they'll find that the air wars are already raging. The Gingrich campaign is going up with an ad hitting Romney on his abortion stance.

"What happened after Massachusetts moderate Mitt Romney changed his position from pro-abortion to pro-life?" says the ad's narrator. "He governed pro-abortion."

Why is Romney vulnerable in South Carolina? As Bloomberg's John McCormick notes, "it's a state where Romney's Northern upbringing and Mormon faith are unnatural fits. South Carolina is also home to companies where workers lost jobs after a private equity firm that Romney helped found, Bain Capital LLC, made investment." http://bloom.bg/wI8Cwz

Expect to hear some of Romney's opponents, namely Gingrich and Rick Perry, try to knock his campaign senseless with attacks on everything from social issues to Bain. But when it comes to that latter attack, Romney says he's convinced it won't work.

"I think their argument fell flat here in New Hampshire," the candidate told ABC's George Stephanopoulos on "Good Morning America" today. "They tried it very hard, ran ads here, were up and down the state campaigning, and people in the state here said, look, we want a guy who spent some time in the private sector, not someone who spent their entire life in Washington.  So I think it's working for my benefit." http://abcn.ws/AhIV29

ROMNEY TO GEORGE: "I'm going to do everything in my power to become that nominee.  I think to post up against President Obama it is essential to have a record of credibility on the economy, and the economy is what I know, it's what I've done all my life and that's why I think I'm the best guy to go up against him," the former Massachusetts governor said on "GMA" this morning. http://abcn.ws/AhIV29 WATCH: http://abcn.ws/zZucmX

THE STAKES IN SOUTH CAROLINA. ABC Political Director Amy Walter notes: "Romney will get a boost from the New Hampshire win that he can take with him to South Carolina. Despite its reputation as a conservative state that differs markedly from Iowa and New Hampshire, voters in South Carolina take their cues from the results of those early contests. South Carolina voters like to be on the side of a winner, and at this point, Romney is the guy who looks like the winner. History is also on Romney's side. Since 1980, no candidate who has lost Iowa and New Hampshire has gone on to win South Carolina." http://abcn.ws/zOHRni

MORE THAN JUST A WIN IN NEW HAMPSHIRE: "The best news for Romney is that the guys who came in second and third place in New Hampshire - Ron Paul and Jon Huntsman - are two of his weakest opponents in the upcoming South Carolina primary. The most recent polling showed Paul in fourth place behind Newt Gingrich and Rick Santorum. Huntsman's moderate profile is going to be a tough sell in deeply conservative South Carolina. Paul is also a very polarizing figure, even within the Republican electorate. In a new ABC News-Washington Post poll, just 40 percent of Republicans view Paul favorably, while 39 percent view him unfavorably. As other candidates drop out, his electoral ceiling will become apparent. Meanwhile, the only two candidates who could give Romney a run for South Carolina, Rick Santorum and Newt Gingrich, just lost a bunch of momentum tonight. They are currently in a battle for a distant fourth place in New Hampshire. With all of these candidates pledging to move onto to South Carolina, it's more than likely that they will once again divide the 'not-Romney' vote, allowing Romney to win with a plurality." http://abcn.ws/zOHRni

READING INTO ROMNEY'S SPEECH. Roll Call's David Drucker heard Romney tweak his message for Palmetto State voters and influencers in his victory speech last night: "After thanking New Hampshire voters for their support, Romney launched into a sharply worded address that checked the boxes on the major issues of concern to South Carolina Republicans, many of whom identify with the tea party movement. One phrase Romney used to describe his plans to address the federal deficit could have been interpreted as an appeal to Sen. Jim DeMint (R-S.C.), who is popular at home and influential in conservative circles nationwide. Obama 'raised the national debt. I will cut, cap and balance the budget,' Romney said. During last summer's fight over the debt ceiling, DeMint and other tea party conservatives backed an alternative plan that they called 'Cut, Cap, Balance.' DeMint endorsed Romney in 2008 but has said he will not endorse a candidate this time around. Meanwhile, Romney has been endorsed by South Carolina Gov. Nikki Haley (R)." http://bit.ly/wq10vl

  THE PSALM BEFORE THE STORM. "If Rick Santorum wants to prove that his near-victory in Iowa wasn't a fluke, then South Carolina is the state where he can try to give Mitt Romney another run for his money," writes ABC's Matt Negrin. "Evangelical voters were key to Santorum's success in Iowa, and the same will probably be true, if not more so, in South Carolina Jan. 21. While leaders in the evangelical community in South Carolina have made clear that Santorum has grabbed their attention, they have cautioned that those conservative voters are still making up their minds, particularly among him, Newt Gingrich and Rick Perry. 'A lot of people are really, really interested in Santorum than they've ever been because of what happened,' said Hal Stevenson, a board member of the Palmetto Family, a conservative group in the state. 'I think it's like night and day.' The economy remains voters' top concern pretty much everywhere, and South Carolina is no exception. But underneath, religious voters have no plans to abandon their values in choosing a candidate, according to pastors at a handful of medium and large evangelical churches." http://abcn.ws/zvLs3E

NEW HAMPSHIRE: BY THE NUMBERS. ABC's Chris Good notes that Mitt Romney not only won a decisive victory in New Hampshire last night, it was more decisive than his former rival's win in 2008. With 77 percent of precincts reporting statewide Tuesday night, Romney had swept every county in New Hampshire except for Coos, which Ron Paul carried. Romney's margin of victory (16 percentage points) figured to be far wider, at night's end, than John McCain's margin of five percentage points in 2008, when the former Arizona defeated Mitt Romney in the Granite State. Four years ago, McCain won New Hampshire with 37 percent of the vote to Romney's 32 percent. Late Tuesday, Romney had won 38 percent of New Hampshire's vote, while his closest competitor, Ron Paul, had 23 percent. In 2008, McCain won every county but two - Hillsborough and Rockingham - both of which Romney carried. http://abcn.ws/Ah2w9l

Missed last night's candidate speeches from New Hampshire? Watch them all in one place: http://abcn.ws/xaELR9

THE BUZZ

RON PAUL SAYS HE'S 'NIPPING' AT ROMNEY'S 'HEELS.' ABC's Jason Volack writes that Ron Paul's second place finish in last night's New Hampshire primary was "validation for the 76-year-old congressmen who has spent an entire political career preaching his free market ideas and non-interventionist ideology, mostly toiling in the confines of political obscurity. Now in the spotlight, Paul admitted that he never expected the groundswell of support, adding: 'I didn't know you were out there.' 'It's no longer that irate, tireless minority that is stirring up the troops, now that irate majority,' said Paul to cheers of 'Ron Paul, President Paul.'" Walking on stage to Tom Petty's 'I Won't Back Down' - after his staff took the stage to the Darth Vader theme from 'Star Wars' - Paul thanked his family, campaign staff, and the Manchester Union Leader for not endorsing him for president. The leading New Hampshire publication endorsed Newt Gingrich." http://abcn.ws/xUaFA6

ROMNEY'S IN THE MONEY. According to the Boston Globe's Matt Viser, the Romney campaign "raised nearly $25 million in the last fundraising quarter, according to several of his fundraisers. The haul will be his biggest yet, and sets a marker against other campaigns that the former Massachusetts governor will be able to mount a long, expensive race that could stretch to multiple states. Romney, whose campaign is trying to recruit fundraisers away from some of his campaign rivals, is also doing a fundraiser on Thursday in Palm Beach, Fla., and next week in New York. His campaign was focused for much of the year on fundraising, but turned in recent weeks almost exclusively to campaigning in early states such as Iowa and New Hampshire." http://bo.st/zoFyi0

SANTORUM CAMPAIGN: 'LOADED FOR BEAR' IN SOUTH CAROLINA. A dispatch from ABC's Shushannah Walshe: Rick Santorum had a disappointing showing in the New Hampshire primary, just cracking double digits late Tuesday evening. Despite the result, Santorum, standing next to his wife Karen, told supporters he would keep fighting. "On to South Carolina," he said to the small group - an equal number of journalists and supporters - gathered at a restaurant here. Santorum's national communications director, Hogan Gidley said they would dump much of the $3 million they have earned since Iowa into the Palmetto State. "We are loaded for bear," Gidley said after Santorum's speech. Santorum said he wanted to "respect the process" by coming to New Hampshire and competing here, adding they wanted to "respect the fact that we are going to campaign in every single state, states that were good for us and states that may be a little tougher." He also gave Romney, the New Hampshire victor, a gracious congratulation, saying the campaign front-runner "fought hard in this state."   http://abcn.ws/x1gLrN

JON HUNTSMAN KEEPS ON KEEPING ON. "Jon Huntsman said a third place finish in New Hampshire is good enough to give him a 'ticket to ride' to the next primary in South Carolina. That's an interesting position for Huntsman, who many consider to be the most liberal candidate in the Republican bunch," ABC's Matt Negrin notes. "Huntsman poured basically his entire campaign effort into New Hampshire and only got to third. Why go forward? The short-term answer is that despite his third-place finish, Huntsman, the former governor of Utah who most recently was President Obama's ambassador to China, is riding out the end of a wave that lifted him up from the very bottom of the polls. The real answer might be more ambitious: Huntsman, 51, might be thinking that he has a shot at winning the White House in four or eight years. South Carolina's primary will be followed closely by the contest in Florida, where Huntsman has a chance to do well - in 2016 or 2020." http://abcn.ws/zhtx7c

WHO'S TWEETING?

@ murphymike : Romney's IA + NH wins give him enough strength that I think he could take a second place loss in SC and still win FL and beyond.

@ jmartpolitico : When u hear the 4th place/15 pct in '08 spin from Mittworld on SC, recall that he bailed at last min and went to NV

@ stefcutter : Romney tries to paint opponents as ag free enterprise.Won't work. Outsourcing, bankrupting companies for profit hardly best of free enterpr.

@ ezraklein : The moderate candidate - or, at least, the relatively moderate candidate - is winning in the GOP primary:  wapo.st/wtzcM5

@ juliannagoldman : Huntsman's Appeal to Independents Provides a Chance to Fight on - Bloomberg via  @BloombergNow  bloom.bg/zARhGv

DISPATCHES FROM THE TRAIL. Check out our new political website OTUSNews.com ( www.Otusnews.com) The Note ( http://abcnews.go.com/blogs/politics/the-note/) and ABC News/Politics ( http://abcnews.go.com/politics) and follow our reporters in the field on Twitter:

Newt Gingrich : ABC's Elicia Dover ( @EliciaDover)

Jon Huntsman and New Hampshire: ABC's Susan Archer ( @TheOnlyArcher)

Ron Paul : ABC's Jason Volack ( @Jason_Volack)

Rick Perry : ABC's Arlette Saenz ( @ArletteSaenz)

Mitt Romney : ABC's Emily Friedman ( @EmilyABC)

Rick Santorum : ABC's Shushannah Walshe ( @shushwalshe) and ABC's Russell Goldman ( @GoldmanRussell)

Check out The Note's Futures Calendar:  http://abcn.ws/ZI9gV

* Get  The Note delivered  to your inbox every day.

* For breaking political news and analysis check out The Note blog:  http://blogs.abcnews.com/thenote/ and ABCNews.com/Politics:  http://abcnews.com/politics