Newt Gingrich swaggered into Florida as a Republican front-runner, but now he’s close to slipping out as an also-ran against a resurgent Mitt Romney.

Gingrich is badly trailing Romney by 11 percentage points, garnering just 31 percent of likely Republican voters heading into Tuesday’s presidential primary, according to a Miami Herald/El Nuevo Herald/Tampa Bay Times poll released late Saturday night.

President Barack Obama should be wary as well. Romney beats Obama by a 48-44 percent spread — a lead inside the error-margin, however — in a theoretical general-election matchup, the poll shows.

In the Republican primary, Romney’s lead looks insurmountable. It cuts across geographic, ethnic and gender lines. And the poll indicates Romney’s attack on Gingrich as a Freddie Mac insider is a hit with GOP voters.

“What does Gingrich need to do? I would say Romney would need to implode,” said Brad Coker, pollster with Mason Dixon Research & Associates, which conducted the survey from Tuesday through Thursday.

“If there’s no 11th hour surprise,” Coker said, “this race is looking right now like it’s over.”

Rick Santorum and Ron Paul — who did not campaign in Florida — are running well behind and have little chance of pulling into serious contention in the nation’s largest swing state, which holds 50 of the 1,144 delegates needed to help secure the GOP’s nomination at this summer’s convention in Tampa.

Late Saturday, former GOP presidential candidate Herman Cain endorsed Newt Gingrich, but it's unclear how that could help Gingrich make up such a big deficit.

Romney is running strongest in Southeast Florida, from the Keys to the Treasure Coast. About half of all voters favor him here. Gingrich gets about a quarter of the vote. Similarly, 52 percent of Hispanic voters favor Romney, compared to just 28 percent who support Gingrich.

Hispanic voters, namely Cuban Americans, have played an outsized role in this election. They account for 72 percent of registered Republicans in Miami-Dade, the state’s most-populous county with about 368,000 GOP voters.

“I’m going to vote for Romney because I think he’s a dedicated businessman,” said Juan Perez, a 69-year-old Cuban Republican and former Port of Miami worker. “At least he has made his own money and is a capable businessman. He is also an ethical and moral man.”

Hispanics account for up to 14 percent of the total ballots cast in a GOP primary in Florida. But they can be pivotal, especially in Miami-Dade, home to nearly 60 percent of all Hispanic Republicans. Miami-Dade’s vote accounted for about half of John McCain’s 2008 statewide margin over Romney in 2008, and it gave Mel Martinez about 90,000 more votes than Bill McCollum in the 2004 Republican Senate race.

As a result, the candidates spent an inordinate amount of time in Miami this past week, visiting the U.S. Hispanic Chamber of Commerce on Wednesday and then returning Friday to the Hispanic Leadership Network and the Latin Builders Association. Romney could be in Cuban-heavy Hialeah on Sunday.

“The Cuban voters here will probably be more homogenous in how they vote than in other parts of the state,” said Dave Custin, a top-tier Miami-Dade political consultant.

“Cubans don’t like to throw their vote away, unless they feel the need to cast a protest vote,” he said. “But Romney does have some problems. Cubans are either Catholic or hard-line Christian-conservative voters. A lot of them don’t like that Romney is Mormon. And they think he’s a Massachusetts liberal. Cubans watch Fox. They listen to Martha Flores at night on Spanish radio. But they listen to Rush Limbaugh during the day.”

Gingrich has strong ties to the exile community for his role as House speaker in 1996 helping pass the Helms-Burton bill into law. The legislation toughened the embargo against Cuba.

But he was badly damaged Wednesday after Miami-Dade’s political icon, Sen. Marco Rubio, scolded Gingrich’s campaign for running an “inflammatory” ad that called Romney “anti-immigrant” for his stances on the DREAM Act and self-deportation — a position that Gingrich has often espoused, except when he’s in Miami.

Perhaps buoyed by Cuban support, Romney appears to be winning the Hispanic vote in a general-election matchup against Obama, who gets 37 percent compared to 53 percent for the former Massachusetts governor. That’s a problem for Democrats who are trying to parlay Latino support for the DREAM Act into a vote against Republicans.

The poll shows Obama winning liberal Southeast Florida, while Romney would take conservative North Florida and Southwest Florida, home to venture-capitalists and businessmen like Gov. Rick Scott. Romney holds statistically insignificant leads in the crucial swing areas of Tampa Bay and Central Florida.

Statewide, Obama handily beats the other Republicans by leads well outside the poll’s error margin — a sign that Gingrich’s support in Florida is weak because he’s not seen as electable as Romney.

By 14 percentage points, Romney is viewed more favorably than Gingrich. And 32 percent view Gingrich unfavorably, compared to only 14 percent who see Romney that way.

Unlike Southeast Florida, Romney’s leads in all other areas of the state are well within the poll’s error margins for each region. Gingrich essentially ties him in North Florida, where Romney is probably doing as well as he is thanks to his strong backing among Jacksonville’s power brokers.

Gingrich also has a gender problem. Women back Romney by a lopsided 19 percentage points over Gingrich, which could be a sign that questions about his three marriages could be haunting him.

Romney’s campaign is more organized and better funded. For weeks, he has been advertising, calling and mailing Republicans in an effort to bank early and absentee votes. But for the few days after South Carolina’s primary that Gingrich won, there’s a good chance Romney won the early-ballot battle.

The poll shows about 47 percent of early voters sided with Romney and 35 percent with Gingrich. About 500,000 GOP ballots have been cast early out of a turnout that could reach roughly two million.

The disorganization from Gingrich’s effort was made apparent when a political committee supporting him started mailing Republicans who had cast ballots three weeks ago.

Gingrich needed a great week. It didn’t happen.

In the hole before he arrived in Florida, Gingrich needed a great week. But he didn’t have one.

Gingrich lacked a core message, and Romney dominated at a Monday debate. On Tuesday, Gingrich lashed out at Romney for hiring former campaign workers for former Gov. Charlie Crist, the Republican-turned-independent who’s a pariah in his old party. Gingrich also invoked Rubio’s name.

Rubio, who vanquished Crist in 2010, essentially told him to quit it. Former Gov. Jeb Bush later echoed the remark. Then, the following day, Rubio criticized Gingrich’s ad. Gingrich pulled it, and later gave a speech on the Space Coast about the need for lunar colonies.

On Thursday, Gingrich burned up time on the campaign trail complaining about being bashed by Romney and his supporters, who might be out-spending Gingrich and his supporters by a 2:1 margin with negative TV ads. Romney then went on to edge Gingrich in the second and final debate that evening, undercutting Gingrich’s line that he alone could manhandle president Obama on stage.

Overall, though, Gingrich is seen by 79-year-old James Kesperson of Destin as the best debater — and therefore the best choice.

“Gingrich is better than what we got,” he said. “Well, he seems to have a little backbone and he’s very knowledgeable and smart.”

But debates might not be enough.

In what looked like a replay of Iowa, where Gingrich collapsed earlier this month, Gingrich burned up precious campaign time complaining about the assault on his character and time as U.S. House speaker. He has acknowledged that all the attacks from the Romney camp have “hurt.”

"This is the desperate last stand of the old order, throwing the kitchen sink, hoping something sticks if only they can drown us in enough mud — raised with money from companies and people who foreclosed on Floridians," Gingrich said Wednesday in Cocoa Beach.

He charged Romney and his super PAC ads were “paid for with the money taken from the people of Florida, by companies like Goldman Sachs.”

Gingrich used a similar, populist attack in South Carolina, where he criticized Romney for heading up Bain Capital, a private equity firm that, at times, profited from closing factories and laying off workers. Gingrich hasn’t used the line here.

In Florida, about three-quarters of Republican voters said they had a positive view of Romney’s business background at Bain Capital. Only 13 percent had a negative impression.

But when asked about Gingrich’s consulting work for Freddie Mac, a majority — 52 percent — had a negative view, compared to 28 percent who saw it positively.

Romney’s campaign has bashed Gingrich’s $1.6 million consulting work for Freddie Mac, which conservatives partly blame for the mortgage mess in Florida, where 1 in 360 properties is in foreclosure.

Romney and the political committee supporting him have spent nearly $17 million in Florida, while Gingrich and the committee backing him have spent less than $5 million.

The pro-Romney/anti-Gingrich message reached Magda Dube, a 48-year-old business owner who voted early in Miami Lakes.

“I voted for Romney. Because Gingrich, I don’t like the fact that he got money from Freddie Mac. Seems a little hypocritical,” she said. “Romney managed to be successful and create a $250 million company.”

Romney’s campaign shifted its attack late Friday by running a new ad that played up the ethics fine levied against him by his fellow members of Congress. The negative ad was a sign that Romney’s campaign still sees Gingrich as a threat and wants to ensure he remains on defense. NBC asked Romney's campaign to pull the ad because it uses the network's news footage."

Gingrich’s campaign and his supporters have recently hit back with ads that link a Bain Capital investment with a company involved in Medicare fraud. The populist attacks might be helping Gingrich nationwide, where the Gallup Poll finds him opening a big lead over Romney.

But in Florida’s primary, only Republicans can vote. And in 2010, they chose a governor whose former hospital company paid a record Medicare fraud-fine

“After we elected Rick Scott, you have to wonder if Medicare fraud really matters as an issue,” Coker said.

“Newt’s problem is consistency. He zigs and zags,” Coker said. “One minute he’s upbeat and positive. The next he’s the attack dog. It’s almost bi-polar. He obviously scares the Republican establishment.”

Miami Herald staff writers Alexandra Leon, Brittany Alana Davis and Adam H. Beasley, along with McClatchy Washington Bureau reporter Lesley Clark contributed to this report.