COLUMBIA, S.C. - Rudy Giuliani's all-or-nothing gamble on Florida is about to play out.

But it's doubtful he'll attract the kind of payoff he needs in the Sunshine State's Republican primary Tuesday to keep his presidential dreams alive.

Despite weeks of intense campaigning, where he promised huge tax cuts and a multibillion-dollar storm relief fund, Giuliani is trailing badly in polls that suggest a very tight race between Arizona Senator John McCain and former Massachusetts governor Mitt Romney.

A Zogby survey released Sunday had McCain and Romney deadlocked with 30 per cent each in the last contest before nearly half the country votes on Feb. 5.

Former Arkansas governor Mike Huckabee was at 14 per cent and Giuliani was behind him with just 13 per cent.

"This is a two-man race," said John Zogby. "It's all coming down to McCain versus Romney."

After spending last year as the national front-runner, Giuliani started losing ground when he skipped the early state votes this month to concentrate on Florida.

It was a risky plan geared to taking advantage of the confusing, wide-open contest and for a while it looked like it could work.

Each of the other top Republicans have won in the early votes - with two big victories in New Hampshire and South Carolina for McCain - but none had been able to completely seal the deal in a crowded field.

Now, with Giuliani's hope fading and Huckabee without a win since Iowa, it's breaking down to the two top contenders.

Romney, who won his native state of Michigan and two virtually uncontested races in Wyoming and Nevada, needs a victory in Florida's hard-fought primary.

For McCain, a solid victory would cement him as the clear party front-runner.

It will be a bit tougher for him in Florida, where he won't have the benefit of independent voters who like his maverick style. The primary is restricted to registered Republicans.

Recent surveys had him leading in California and Giuliani's home state of New York, two of the most important battlegrounds on so-called Super Tuesday.

The high stakes are reverberating on the campaign trail, where McCain and Romney have been trading bitter barbs.

Romney, who is a multimillionaire thanks to an investment firm he started, is portraying himself as just the person to stop the United States from sliding into a recession as he attacks McCain's emphasis on foreign affairs.

Meantime, McCain, a Vietnam War hero, has emphasized national security, saying it will remain the real issue in the U.S. "even if the economy is the, quote, No. 1 issue."

After McCain accused Romney of supporting a timetable for withdrawing U.S. troops from Iraq, Romney blurted out that his rival was "lying" before altering his worlds to "he made a dishonest comment."

"If we surrender and wave the flag, like Senator (Hillary) Clinton wants to do and withdraw, as Governor Romney wanted to do, then there will be chaos, genocide," said McCain.

He was endorsed this weekend by Florida Gov. Charlie Crist, who is widely popular.

Romney picked up the backing of diplomat Liz Cheney, daughter of Vice-President Dick Cheney and a top official for Fred Thompson until he dropped out of the Republican race last week.

As for Giuliani, he has become the butt of jokes from late-night talk show hosts. David Letterman said recently the former New York mayor would soon be appearing on a TV show - Without a Trace.

The New York Times also offered up a scathing portrayal of Giuliani, who had won the respect of many for how he handled the aftermath of the 2001 terrorist attacks.

An editorial late last week described him as a man whose "arrogance and bad judgment are breathtaking.

"For Giuliani, Florida has followed a familiar and disturbing pattern. The more the voters see of the man, the less they seem to like him. In the state that will decide the fate of his candidancy, he is weaker today than when he started."

Giuliani has irked conservatives with his liberal views on key social issues and a messy personal life with three marriages and two children who are estranged from him.

Huckabee, too, has had his problems. The folksy former Baptist minister held appeal for evangelicals but hasn't been able to reassure a lot of voters he has the depth to be president with his lack of foreign policy experience.

Romney, a Mormon, has been criticized for flip-flopping on social issues for political gain. And McCain's individualism has angered many in the party base.

The less positive qualities of each of the candidates have kept Republicans from settling on one in a critical election year when Democrats have a good chance of taking back the White House.

Democrats are also voting in Florida but no delegates will be awarded to either Clinton or Barack Obama because party officials were angry the state ignored rules and moved up its vote.

Still, Clinton planned to visit the state after the polls close Tuesday to thank supporters.