By Jane Sutton

MIAMI (Reuters) - Newt Gingrich struggled to regain momentum in the Republican presidential race on Friday as two new polls showed him falling behind rival Mitt Romney, who was seen as the winner of the final debate before the Florida primary.

The White House contenders courted Florida's sizable Hispanic vote, many of them Cubans, with appearances on Friday at the Hispanic Leadership Network, where Romney received an unusually warm reception and the reaction to Gingrich was more sedate.

Bouncing back after losing the South Carolina primary to Gingrich on Saturday, Romney had an 8-percentage point lead over him in a Reuters/Ipsos poll released on Friday. A Quinnipiac University poll gave him a 9-percentage point edge.

The Reuters/Ipsos online poll gave Romney 41 percent and Gingrich 33 percent ahead of Saturday's contest.

That margin is similar to three polls released on Thursday that all showed Romney taking control of the battle in Florida, where the former Massachusetts governor enjoys a financial and organizational advantage over Gingrich.

Romney battered the former House of Representatives speaker in two debates this week, wounding him in the same format that has helped fuel Gingrich's campaign.

"With the debates now over, Gingrich will need some other way to reverse the tide that appears to be going against him," Quinnipiac University pollster Peter Brown said.

Tuesday's Florida primary is the fourth contest in the state-by-state battle for the Republican nomination to challenge President Barack Obama, a Democrat, in the November 6 U.S. election. Romney won in New Hampshire and former Senator Rick Santorum won the first contest in Iowa.

Romney repeatedly attacked Gingrich at Thursday's debate in Florida, scoring points on immigration, candidates' finances and even lunar exploration.

"That was Romney on Red Bull," Republican strategist Ron Bonjean said. "You could tell Newt was tired, he's carrying a heavy load. He was counting on pure momentum to carry him through Florida, and that momentum has stopped."

At a campaign event in Cape Canaveral, Florida, Romney reminded the crowd of his debate performance.

"How about that debate last night? Wasn't that fun?" Romney asked. "I've had the fun of two debates where I had to stand up and battle, and battling was fun."

'CUBA WILL BE FREE'

An energized Romney, whom Gingrich has described as the most anti-immigrant candidate in the Republican race, won several standing ovations from the Hispanic crowd in Miami earlier on Friday.

"There is a time coming soon when Cuba will be free," Romney told them, adding "America can't sit back" in dealing with the island nation off the coast of Florida.

Gingrich received a much quieter response, once again mocking Romney's call for "self-deportation" of illegal immigrants as "a fantasy. It's not a solution."

Gingrich said the concept might work for younger illegal immigrants who had been in the United States a short time, but not for older immigrants with deep family ties. They should be allowed to apply for citizenship through local councils similar to draft boards, he said.

A Florida win for Romney would put him in a strong position to capture the nomination as the primary map tilts in his favor in February with contests in seven states where he has the potential for strong showings.

Next up on February 4 is Nevada, where Romney won with 51 percent of the vote during his failed 2008 presidential bid. On February 7 Minnesota and Colorado hold caucuses and Missouri holds a primary. Gingrich did not make the ballot in Missouri.

Four of the states with February contests - Nevada, Maine, Colorado and Minnesota - use caucus systems, which often require greater organization to rally voter turnout. That could help Romney take advantage of his superior financial and staff resources.

On February 28, Michigan and Arizona hold primaries. Romney was raised in Michigan, where his father was a governor and car executive.

A new Gingrich television ad in Florida asked: "What kind of man would mislead, distort and deceive just to win an election?"

"This man would be Mitt Romney," the ad's narrator said.

Romney's camp said the sharp tone from Gingrich was a sign he was desperate to distract from his own record as House speaker, where he faced an ethics probe, and as a consultant with mortgage giant Freddie Mac.

"It is laughable to see lectures on honesty coming from a paid influence peddler who suffered an unprecedented ethics reprimand, was forced to pay a $300,000 penalty, and resigned in disgrace at the hands of his own party," Romney spokeswoman Andrea Saul said.

(Writing by John Whitesides; editing by Alistair Bell and Mohammad Zargham)