WASHINGTON (Reuters) - Mitt Romney's expected romp to the Republican presidential nomination turned into a long and hard slog on Saturday, and he leaves South Carolina as a damaged and suddenly vulnerable candidate.

But beyond the take-back-our-country frenzy that Newt Gingrich was able to whip up among conservative voters in the Palmetto State, Romney still has significant advantages over Gingrich as the race heads to Florida and beyond.

Romney's past week in South Carolina hardly could have been worse.

In two debates the private equity executive with an estimated worth of $270 million fumbled questions about when he would release his tax returns, acknowledged that his tax rate was well below those of most wage-earning Americans, and generally allowed Gingrich to cast him as an out-of-touch elitist.

Meanwhile, the long list of Gingrich's peccadilloes that polls have said make him unelectable to many Americans -- his cheating on his first two wives, the ethics probe when he was U.S. House of Representatives speaker, his unapologetic tendency to say things some view as racially insensitive - were swept aside by his strong performances in televised debates before conservative crowds.

By the time Gingrich's dominating win in South Carolina was tabulated late on Saturday, it was clear that the race for the Republican nomination is led by two flawed candidates.

It also was clear that Romney, a former Massachusetts governor, is better equipped than Gingrich for the bumpy ride ahead in the race to determine which Republican will face Democratic President Barack Obama in the November 6 election.

As the campaign heads to a January 31 primary in Florida - a large, diverse state where campaigning is particularly expensive - Romney will have more chances to flex his financial and organizational muscle over Gingrich and former Pennsylvania senator Rick Santorum, who finished third in South Carolina.

The campaigns are not due to file expense reports until the end of the month. But some of the spending by the political action committees (PACs) that support them has been reported to federal election officials, and shows that the PAC backing Romney has spent millions in Florida since mid-December, far more than any other PAC.

"What this looks like now is what Romney has planned for all along - a long, hard campaign," Republican strategist Ron Bonjean said. "Romney has the money and the organization in place in states where other candidates haven't even thought about going yet."


For Gingrich, the challenge will be turning the momentum he won in South Carolina into a self-sustaining organization that can raise money and build support beyond the early states.

In the first week of February, five more states hold nominating contests - Nevada, Maine, Colorado, Minnesota and Missouri. Arizona and Michigan have contests late in the month.

Romney has been organizing in those states for months. Gingrich is far behind in doing so, and failed to even make the ballot in Missouri.

Beyond his organization, Romney has other advantages in the February contests. As a presidential candidate in 2008, he won Nevada easily with more than 50 percent of the vote. He grew up in Michigan, where his father, George, was a governor and auto executive.

Four of the states - Nevada, Maine, Colorado and Minnesota - are caucus states where get-out-the-vote campaign organizations can be critical.

"Momentum and excitement only take you so far," said Saul Anuzis, former chairman of the Michigan Republican Party.

"Gingrich's biggest challenge going forward is his record, but he also has an organizational challenge in that he has not put together a national campaign," he said.

In claiming victory late Saturday, Gingrich acknowledged as much.

"I need your help in reaching out to people in Florida," Gingrich told supporters. "We don't have the kind of money that at least one of the candidates does. But we do have ideas and we do have people and we've proved here in South Carolina that people power with the right ideas beats big money. And with your help we're going to prove it again in Florida. "

There are two debates in Florida this week, which could be good news for Gingrich if he can continue performing well in such settings.

Romney will be under immense pressure to shine in the debates or face growing doubts from a Republican establishment that so far has been falling in line behind him.

Romney signaled on Saturday he will take a far more aggressive approach against Gingrich and remind voters of the former House speaker's mixed record. In South Carolina, Romney raised Gingrich's ethics violations as House speaker.

"Our party can't be led to victory by someone who has never run a business and never run a state," Romney said after the South Carolina results were in, comparing Gingrich with Obama.

Florida is more diverse and less conservative state than South Carolina with large concentrations of elderly, Hispanic and Jewish voters - putting Social Security and immigration in the spotlight - and an unemployment rate of 10 percent, far above the national average.

Romney leads Gingrich in opinion polls in Florida by double digits, but Gingrich showed in South Carolina he can wipe out a lead of that size in a week.


Gingrich made headway against Romney in South Carolina by attacking his work for Bain Capital, a private equity firm, and questioning his refusal to release his tax returns.

It's unclear whether those issues will play well in Florida.

"Newt had one of the best weeks in politics I've ever seen and Romney had one of the worst," said Republican strategist Rich Galen, a former Gingrich aide. "But how many times can you say, 'When will you release your taxes?' It's been asked and answered."

Romney has had staff and phone banks operating in Florida for months. The campaign also has encouraged voters to cast ballots before Election Day, flooding them with mail and phone calls for months. Early voting has already started in Florida.

"Gingrich will carry momentum into Florida, but his campaign doesn't appear to be as durable for the long haul," said Republican strategist Adam Temple of South Carolina.

"He's not on the ballot in Virginia, appears to be lacking in Nevada organization and continues to carry baggage that won't go away," he said.

The South Carolina result showed Romney still has trouble winning over conservatives who remember his past support for abortion rights and an individual healthcare mandate when he was governor of Massachusetts.

"There is still a fairly hard ceiling to Romney's support among Republican voters," said Dan Schnur, an aide to eventual Republican nominee John McCain during his 2000 campaign. "But I don't know that they are rejecting Romney as much as demanding more evidence. They want him to earn it."

(Editing by David Lindsey and Will Dunham)

[Photo by Christopher Halloran / Shutterstock.com.]

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