Republican presidential contender Newt Gingrich assailed his chief rival for the party’s nomination on Tuesday by using a local insult, calling Mitt Romney the “Charlie Crist” of the GOP field.

His reference to the former Florida governor, who lost his Senate race in 2010, embodies Gingrich’s strategy as he tries to ride a wave of momentum heading into the primary here next week: to channel the energy and power of the tea party movement that sank Crist and elected outsider superstar Marco Rubio.

Gingrich has attached himself to the tea party movement ever more tightly in recent days, casting himself as an antiestablishment revolutionary who understands the movement’s rage against President Obama. He has embraced the endorsement of former Alaska governor Sarah Palin. He has promised that he would put Texas Gov. Rick Perry, a former presidential rival, in charge of a commission studying the 10th Amendment, a rallying cry for tea partyers who believe Washington has repeatedly violated that provision of the Constitution by usurping the powers of the states.

In the most recent contest, on Saturday in South Carolina, Gingrich’s tea party embrace worked: He won the primary with the overwhelming backing of tea party supporters, beating Romney in that group of voters by about 20 percentage points.

Yet it remains unclear whether the tea party is as vibrant nationwide as it was three years ago. Even more untested is the movement’s ability to shift opinion at the presidential level, especially against leaders of the Republican establishment who think Romney would be more electable against Obama.

Florida — which launched the careers of Rubio and Gov. Rick Scott, two of the tea party’s most prominent figures — may be the perfect setting to learn the answer.

Both sides are aware of that dynamic. Gingrich has developed a vast network of tea party support nationally, particularly in Florida; 42 grass-roots groups across the Sunshine State have endorsed him and will join him on Thursday for a tea party rally near Orlando.

Gingrich began the day Tuesday at a diner in St. Petersburg, where he told a packed room of supporters, “As many of you know, Jose Mallea is helping us with our campaign, Marco Rubio’s campaign manager.” The mere mention of Rubio drew cheers, and Gingrich’s next line, comparing Romney to Crist, received boos.

“We saw last night that Mitt Romney has picked up Charlie Crist’s campaign,” Gingrich said, referring to several former Crist advisers who work for Romney. “I sort of think that tells you everything you need to know about this primary.”

Romney pushed back against the comparison to Crist. The candidate noted that he endorsed Rubio for Senate before Crist left the Republican Party to run as an independent. And, he said, it would be absurd to judge a candidate based on his staff’s previous employers — with a dig at Gingrich over his own campaign woes.

“Maybe because he lost his whole staff, he’s consumed with other people’s staff. I don’t think this is about staff, I think this is about the candidate,” Romney said.

Romney has renewed his efforts to undercut Gingrich’s claim of outsider status, hammering home his work for the mortgage giant Freddie Mac, describing the former House speaker as a “Washington insider” who “peddled influence” on behalf of his clients.

On Tuesday, Romney addressed a crowd in front of a house in Fort Myers with a red “foreclosed” sign in the yard.

“One thing I know he was doing is he was standing up as the former speaker of the House and someone many people respected as a conservative leader. He was standing up and defending Freddie Mac,” he told the gathering of a few hundred people. “And so conservatives in Congress and conservatives around the country, instead of arguing to get rid of these entities, to scale them back and let the free market work, they said, ‘Well, if Newt Gingrich thinks it’s a good idea, then we ought to go along with it.’

“You get paid, and then you go out and say things that influence other people,” Romney continued. “That’s the nature of what’s been going on in this country. It is wrong. We can’t have influence peddlers leading our party.”

As the tug-of-war over outsider status continued, advisers to Gingrich pushed hard on the comparisons between Romney and Crist, saying their similarities speak to the overall dynamic of the race — and will resonate in Florida.

“Charlie Crist was the establishment candidate,” Mallea said. “He was well-funded. He had all the high-profile endorsements.”

But Gingrich, like Rubio, “has a bold agenda and wants to go to D.C. and shake things up,” he added.

Not every voter agrees. Bob Ide, 60, a retired insurance man from Cape Coral, said the Freddie Mac contract proves that Gingrich is not the outsider he has portrayed. “It was basically a kickback. It was that kind of money, basically just to be their friend.”

“He’s no outsider — he’s been running for president for years,” said Ide, who supports Romney. He said the tea party will play a role, “but the election is bigger than them.”

“Republicans are charged, Democrats are charged,” Ide said. “It’s going to be wild.”

Staff writer Philip Rucker in Washington contributed to this report.