| GILBERT, South Carolina
GILBERT, South Carolina With the crucial Republican presidential primary in South Carolina just hours away, front-runner Mitt Romney on Friday lowered expectations for how well he will do and acknowledged he is in a neck-and-neck race with Newt Gingrich.
"Speaker Gingrich is from a neighboring state, well-known, popular in the state, so I knew we'd have a long road ahead of us, and frankly to be in a neck-and-neck race at this last moment is kind of exciting," Romney told reporters.
Polls show Gingrich, who is from Georgia and is former speaker of the House of Representatives, gaining on Romney. The former Massachusetts governor's attempt to launch a knockout blow in the nomination race by winning the conservative southern state on Saturday is now in doubt.
Romney had another mixed debate performance Thursday night when he struggled to fend off queries about releasing his tax returns, after acknowledging this week that he pays a much lower tax rate than many working Americans. The former executive has an estimated worth of $270 million.
But Romney can afford to come in second in South Carolina and still remain at the head of the pack of Republicans.
He has more campaign funds and a stronger organization than Gingrich and the two other Republican contenders, former Pennsylvania Senator Rick Santorum and Texas Congressman Ron Paul.
Such advantages for Romney could be key in Florida, where the January 31 primary is next in the state-by-state contest to determine who will face Democratic President Barack Obama in the November 6 elections.
Florida is one of the country's largest states, with several major media markets. Maintaining a traveling campaign and covering the state with TV ads is more expensive there than in most other states.
"I'm still hoping and planning to win here" in South Carolina, Romney said. "I'm sure the speaker feels the same way I do, but we're going to go on for a long race and I think I've got the staying power and a message that I believe connects with people."
An online Reuters/Ipsos poll on Thursday showed the South Carolina race tightening with Romney at 35 percent support, Gingrich with 23 percent and Santorum with 15 percent.
The poll listed 6 percent support for Texas Governor Rick Perry, who left the race on Thursday and endorsed Gingrich. The poll also has a "credibility interval" - similar to a margin of error - of 4.5 percent for each candidate's result.
So if he can collect most of Perry's support, Gingrich could be within striking distance of Romney.
In an apparent dig at Gingrich, Romney said the Republican nominee needs to have "vision, trust, honesty, character, integrity."
Gingrich has faced questions about claims by his former wife Marianne in an ABC interview on Thursday that he had sought an "open marriage" when he was having an affair in the 1990s with Callista Bisek, who later became Gingrich's third wife.
Gingrich denied his former wife's allegation.
The Republican candidates tore into each other on Thursday and Gingrich snarled at the CNN moderator for asking about the open marriage issue in a raucous TV debate.
It came at the end of one of the campaign's most tumultuous days, with Perry dropping out and Santorum emerging as the leader of the Iowa caucuses held more than two weeks ago. Romney initially was called the winner in Iowa by eight votes.
Gingrich missed a chance on Friday to follow up on his strong debate performance when he canceled an appearance at a Republican Party conference in Charleston because of a small crowd.
Although only a minor blip in a long campaign, the cancellation again raised questions about whether Gingrich is disciplined enough to win the nomination and then go on to beat Obama in November.
"He gave his word that he was coming here and at the last second, something better came along," said Ann Sullivan, a Republican from North Carolina attending the conference.
(Writing by Alistair Bell; Additional reporting by Colleen Jenkins; Editing by Vicki Allen)