Newt Gingrich moved quickly Sunday to capi­tal­ize on his victory in the South Carolina primary, launching an aggressive fundraising and organizing effort and casting himself as the only candidate thus far to have captured the enthusiasm of the Republican base.

On a blitz of the Sunday morning talk shows, Gingrich credited his victory to his two debate performances last week in which he said he was able to articulate the “real pain” felt by South Carolina voters over the weak economy and tap into a deep anger against the political establishment, including the news media.

He predicted his message will resonate with voters in Florida, which holds the next primary Jan. 31.

“People are just sick and tired of being told what they’re allowed to think, what they’re allowed to say,” Gingrich told NBC “Meet the Press” moderator David Gregory. “As they look at the big boys in Wall Street, as they look at Washington, they know none of the help got down to average everyday Floridians, and I think that gap creates a real anger against the national establishment.”

But a more difficult hurdle lies ahead for Gingrich as the race pivots to the populous and politically diverse state further south, where Romney’s well-organized campaign apparatus has been operating for weeks, racking up endorsements and blanketing the airwaves with TV ads.

Romney has been spending heavily on television advertising in each of the state’s 10 media markets, and he plans a week of campaigning across the state beginning Sunday. He has focused some attention on the Cuban-American population, a group that heavily supported John McCain in 2008.

Romney’s advisers believe his economic message and business experience will play well with voters in Florida, a business-friendly state that has been suffering one of the nation’s highest unemployment rates. But they do not plan to let up on the attacks on Gingrich’s character, particularly his two failed marriages and a recent interview from his second wife Marianne in which she alleged that Gingrich asked for an “open marriage,” a claim Gingrich denied.

“If we put up anything less than a Boy Scout, we’re gonna be in trouble,” said Rep. Jason Chaffetz (R-Utah) in an interview.

“I don’t believe that voters in Florida will find that media bias trumps serial philandering,” added Chaffetz, who has endorsed Romney and served as a surrogate on the campaign trail. “I think when the reality of that question settles in for conservatives, they’re not going to stand for somebody who’s had trouble in these areas. I really don’t. I think voters in a rational moment will see how devastating and stupid that would be to hand that card to Barack Obama.”

Romney also has the endorsements of three prominent leaders there — Reps. Ileana Ros-Lehtinen and Mario Diaz-Balart, as well as his brother, former congressman Lincoln Diaz-Balart — and last week began running a Spanish-language television advertisement narrated by Romney’s Spanish-speaking son, Craig.

Cognizant of the challenges that lie ahead, Gingrich’s campaign and its supporters are mounting an aggressive effort to at least partially close the fundraising and organizational gap.

The former House speaker’s campaign plans to announce today that it raised $1 million in eight hours, including a single moment during his victory speech Saturday evening when 4,000 donors were giving online at the exact same time, according to the campaign’s vendor.

In addition, a super PAC supporting Gingrich will launch a TV advertising campaign on Tuesday continuing its attacks on Mitt Romney. The committee is expected to continue highlighting Romney’s work for the venture capital firm Bain Capital, including its takeover of Damon Clinical Laboratories, a company that was fined nearly $120 million amid accusations of Medicare fraud. Romney’s supporters already have started running tough anti-Gingrich television ads in Florida.

Though Gingrich’s immediate task will be to focus on Florida, he already has his sights set on the following contest in Nevada, where Romney is believed to have a significant advantage in part because of its large Mormon population. The Gingrich campaign is adding staff there and a political action committee backing him is already building a field operation in advance of the Feb. 4 caucuses.

Though Gingrich is ramping up his campaign, he is unlikely to hire any political consultants or add too many of the trappings of a traditional campaign organization, focusing instead on the debates, meeting voters and airing his “big ideas.” In a debate Thursday night, Gingrich said that if he could have done anything differently thus far in his campaign, “I would skip the first three months where I hired regular consultants.”

Gingrich’s 2-point win in South Carolina represented a swift and extraordinary turnaround in his fortunes.

After disappointing distant finishes in the Iowa caucuses and the New Hampshire primary, Gingrich had limped into South Carolina more than 10 points down in most polls. So battered was his candidacy that Gingrich himself had conceded that his campaign might be over if he failed to turn in a strong performance.

His victory not only changes the near-term dynamic of this presidential campaign but also defies political history. South Carolina is known as a firewall for the GOP establishment in presidential contests, traditionally extinguishing the hopes of insurgent candidates such as Gingrich.

This year also marks the first time that a different Republican candidate has won each of the first trio of contests — still further evidence of how unsettled and dissatisfied the party’s voters are in a year when they are anxious to unseat a vulnerable incumbent president.

On “Fox News Sunday,” Romney acknowledged that it had been a rough week for his campaign but predicted that he would right the ship in subsequent contests. He began by agreeing to release his tax returns for 2010 and an estimate for 2011, which he said he plans to post on his Web site Tuesday — an attempt by the campaign to quiet the growing criticism over his handling of his personal wealth.

“You know, in my experience, a lot of people face setbacks, and you come back from them,” Romney told host Chris Wallace. “And that’s the way to be successful, is to come back from the inevitable downturns. We’re hoping and expecting to do that down the road.”

Romney called South Carolina “Newt’s neighborhood,” referring to the fact that Gingrich served as a congressman from neighboring Georgia but also alluding to the influence of its evangelical Christian base. Exit polls suggest Romney’s Mormon faith may have contributed to his loss there.

However, he said, “I don’t think in the final analysis that religion is going to play a big factor in selecting our nominee.”

While Romney’s team sees Florida as a critical state for him to win, they are looking ahead to February contests in Nevada, Colorado, Maine, Michigan and Arizona. Romney has paid staff and volunteer networks in many of those states, in particular Nevada, which boasts a large Mormon population that helped propel Romney to victory there in 2008, and Michigan, where Romney was raised and where his father, George, served three terms as governor.

Since 1980, every South Carolina GOP primary winner has gone on to win the party’s nomination. But how far this victory will carry Gingrich remains very much in question.

Gingrich’s team acknowledges that he suffered some self-inflicted damage by taking that hard line against Romney in New Hampshire.

In addition to regaining his footing, strategists say the former speaker confronted two major challenges in South Carolina: He had to convince voters here that he could take on Obama in the fall, and he had to stir doubts about Romney’s electability, character and conservatism.

How well he succeeded at both of those goals was apparent in the exit polls. Unlike in Iowa and New Hampshire, Gingrich came out ahead of Romney among those voters who said that an ability to win in November was the quality they were looking for most in a candidate.

As Gingrich took the stage Saturday night to give his victory speech, his supporters chanted: “Newt can win!”

In another sign of how he had changed the dynamic of the race, Gingrich outpolled Romney 4 to 3 among voters who rated the economy as their greatest concern — even though economic expertise has been one of Romney’s chief selling points.

Exit polls also showed that Gingrich had a bigger advantage among voters without college degrees than college grads, and that he did especially well among voters who were “falling behind financially” or “holding steady” while Romney about tied him among those who were “getting ahead.”

The data give credibility to Gingrich’s assertion that his message resonates best with voters who have been most hurt by the economy — and offer his campaign some hope as the campaign turns to a state that has been deeply affected by the downturn, particularly the housing crisis.

It was not the first resurrection that Gingrich has experienced during the course of the campaign. His operation collapsed last summer, when much of his staff quit over disagreements about his unconventional strategy. And then when he rebounded in the late fall, an outside political organization backing Romney unleashed millions of dollars worth of ads against Gingrich in Iowa that helped deflate his candidacy there.

Things began to turn his way again in the first of two debates last week. When Fox News Channel moderator Juan Williams asked whether Gingrich’s characterization of Obama as a “food stamp president” carried racial overtones, the former speaker brought the Myrtle Beach audience to its feet with a denunciation of political correctness and a passionate defense of the work ethic.

“The debate Monday night may have been a game changer,” Gingrich said in an interview with The Washington Post two days later.

However, the week leading up to the primary had more than its share of unexpected twists.

Gingrich received a boost when one of his rivals, Texas Gov. Rick Perry, abruptly dropped out of the race and endorsed him. Gingrich also picked up the backing of tea party heroine Sarah Palin, the former governor of Alaska.

Romney was also dealt a setback, at least in bragging rights, when the Iowa Republican Party reversed its earlier determination and declared that former senator Rick Santorum (Pa.) had won the Jan. 3 caucuses. That switch may ultimately prove to be a blessing for Romney because it gives Santorum, who placed a distant third in South Carolina, a rationale to remain in a race in which he is fighting with Gingrich over conservative voters.

However, Gingrich also found himself on the defensive, when his second wife, Marianne, accused him in interviews with ABC News and The Post of wanting an “open marriage” in which he could divide his affections between her and the mistress who became his third wife.

When asked about those allegations during Thursday night’s debate, Gingrich turned the tables on moderator John King of CNN.

Exit polls suggest the jujitsu was successful. Gingrich fared well among both evangelical voters and women — two groups whose support might have been shaken by his ex-wife’s interview.

Meanwhile, Romney stumbled in the debates, particularly in his convoluted explanations of why he has not yet released his tax returns, which served as a reminder of his wealth.

Overall, the debates proved to be a decisive factor in South Carolina.

In preliminary exit polls, more than half of voters say they decided in the closing days of the campaign, and Gingrich held a roughly 20-point lead in this group. Romney matched Gingrich among those who decided earlier.

Gingrich’s strongest support came from those who said the debates had been the “most important factor” in making their choice.

“It’s not that I am a great debater, it is that I articulate the deepest-felt values of the American people,” Gingrich said in his victory speech.

Two more debates are scheduled for this week in Florida, one Monday and another Thursday.

Though Romney’s participation in those debates had been in question, his campaign confirmed Saturday that he will appear at both — which was welcome news to Gingrich’s team.

Another factor contributing to Gingrich’s success was the outside spending by a “super PAC” supporting his candidacy. Shortly before the South Carolina contest, it received a $5 million contribution from Las Vegas casino magnate Sheldon Adelson.

Going into Florida, “we will raise a boatload of money, and then we will do what we did in South Carolina,” said Rick Tyler, a former Gingrich aide who runs the Winning Our Future super PAC.

Polling director Jon Cohen and staff writers Philip Rucker, Amy Gardner and Scott Clement contributed to this report.