Republican presidential hopeful Mitt Romney addresses the Hispanic Leadership Network at Doral Golf Resort in Miami.

With only three days to go until the vital Florida primary, the two rivals Saturday barnstormed the huge battleground state which could prove a make-or-break stop in their battle for the Republican Party crown.

After a shock defeat by Gingrich in South Carolina last weekend and a slew of attacks, Romney's campaign got a fresh boost as he bids to be the party's nominee to take on Democratic President Barack Obama in the November elections.

A Quinnipiac University survey showed the former Massachusetts governor at 38-29 percent over former House of Representatives speaker Gingrich in Florida, re-capturing the lead after slipping badly over recent days.

The poll of likely Republican voters was taken before the candidates' televised debate on Thursday, but it indicated the race may be swinging back in favor of multimillionaire businessman and former venture capitalist Romney.

"Newt Gingrich's momentum from his South Carolina victory appears to have stalled and governor Mitt Romney seems to be pulling away in Florida," said Peter Brown, assistant director of the Quinnipiac University Polling Institute.

Texas congressman Ron Paul, who has done virtually no campaigning in the Sunshine state, was on 14 percent, and former Pennsylvania senator Rick Santorum was in fourth place, with 12 percent, the survey said.

The field has now narrowed in Florida to a two-man race between Romney and Gingrich, who traded bitter attacks in a debate late Thursday.

Gingrich supporters were still firmly behind their man, manning the phones and handing out pamphlets in the final countdown towards Tuesday's Republican presidential primary here.

"The country is underwater, the house is flooded, we want the best plumber regardless of the flaws he can have," said campaign official Bert Ralston at Gingrich's Jacksonville headquarters.

After a string of debates where he was criticized for lacking passion, Romney came out swinging late Thursday, rounding on Gingrich for alleging he was against immigrants and dodged his taxes.

"The idea that I'm anti-immigrant is repulsive," Romney insisted, showing a flash of steel seldom seen in his campaign.

Immigration policy is high on the agenda in Florida, a vote-rich battleground state where the large Hispanic bloc forms a key constituency.

On Friday, Romney pledged at a conference organized by the Hispanic Leadership Network that he would appoint "a presidential envoy responsible for democracy and freedom in Latin America."

He scored another important victory later in the day when he secured the endorsement of Puerto Rico Governor Luis Fortuno.

"Mitt Romney is the one candidate who has the record, leadership, experience, and pro-growth plan to continue the course of private-sector job creation we've begun in Puerto Rico and provide economic stability for generations," said Fortuno, who appeared with Romney at a campaign rally in Orlando, Florida.

Meanwhile, former Florida governor Jeb Bush, brother of ex-president George W. Bush, warned that the candidates ignored the Hispanic community at their peril.

"If we ignore the aspirational nature of the Hispanic communities across the country and say, 'well, we can just keep doing it the old way', and expect a different result, I think conservative candidates will lose," Bush said.

Romney already has a win in New Hampshire under his belt, and a victory in Florida on Tuesday could once again anoint him as the man to beat in the race.

Gingrich was often caught off guard in Thursday's debate and his usual agility in mounting a pugnacious counter-attack seemed to desert him.

Such was the heat of early exchanges that Gingrich offered a truce: "How about if the four of us agree for the rest of the evening, we're going to talk about issues?"

But the offer was quickly knocked down when Gingrich refused to answer for earlier remarks about Romney's Swiss and Cayman Island bank accounts.

Instead Romney went on the attack. "Wouldn't it be nice if people didn't make accusations somewhere else that they weren't willing to make here?" Romney asked rhetorically.

He also ripped Gingrich's plans to establish a permanent base on the moon, largely with private funding.

"It may be a big idea, but it's not a good idea," Romney said.

Addressing a rally on Friday, Romney said, "How about that debate last night ... Battling was fun and battling was won, I can tell you."