PORT ST. LUCIE, Fla. — Ringed by cameras, the agents of the Newt Gingrich and Mitt Romney campaigns squared off for yet another duel.

“Has Newt answered the question about Freddie Mac yet? ... What kind of influence was he peddling?” asked Rep. Connie Mack IV, R-Fla., one of a series of members of Congress trailing Gingrich at events to give Romney counter-messages to reporters.

“Peddling, that would be what Vin Weber did,” said R.C. Hammond, Gingrich’s acerbic spokesman, referring to a Romney adviser who lobbied for the government-backed mortgage lender. Gingrich consulted for Freddie Mac but never registered as a lobbyist.

“You should answer the question. It might help the campaign,” Mack replied.

The problem for Gingrich is that those skirmishes have been more fiery than his own pair of debate performances this past week, a span that has seen him plummet from the high of his South Carolina triumph to trailing by 8 to 10 percentage points in polls leading up to Tuesday’s Florida primary. The dramatic swing was visible in Gingrich’s demeanor as he raced through Florida.

Last Tuesday night, the former House speaker from Georgia drew an astounding 6,000 people to a rally in Naples, where he closed with a general election-style message: “I say to every Democrat, every independent across America, we want you to feel free to join in because together we are going to change Washington.”

Fewer than 48 hours later, Gingrich devoted the first 10 minutes of a tea party rally speech in Mount Dora to lashing out at Romney. He acknowledged he had been wounded and he was angry.

“We’re not going to beat Barack Obama with some guy who has Swiss bank accounts, Cayman Island accounts, owns shares of Goldman Sachs while it forecloses on Florida and is himself a stockholder in Fannie Mae and Freddie Mac while he tries to think the rest of us are too stupid to put the dots together to understand what this is all about,” he said.

Romney turned that comment around on him at Thursday night’s debate after his research team unearthed evidence that Gingrich also had held Freddie Mac and Fannie Mae stock. Gingrich had no ready reply for when Romney sprang his revelation.

Explaining his passivity, Gingrich said Saturday at a Port St. Lucie news conference that he had been befuddled because Romney was untruthful.

“A couple scenes, you can go back and replay, I’m staring in amazement,” he said. “I know what he’s saying is untrue. And I also know that in that particular audience it would not have worked to take him head on.”

Gingrich’s campaign has become haphazard, with the schedule often changing and Gingrich perpetually late. Saturday in particular, he seemed drained.

From Port St. Lucie, he traveled to a Hispanic town hall forum at a church in Orlando, where he was greeted by a sparse crowd of about 75 people. Among them was Ralph Oropesa, 30, who said he would decide Tuesday between Gingrich and former Pennsylvania Sen. Rick Santorum, based on who needs his vote more to take down Romney.

“Newt’s Newt,” he said, shrugging. “Sometimes you hate him, sometimes you love him.”

“I liked him a lot in South Carolina,” he added, but said that in Florida, Gingrich seems like a football team trying to run out the clock with conservative play-calling.

By Saturday night, though, Gingrich was buoyed by an endorsement from former presidential candidate Herman Cain, who had said previously he would not endorse a GOP primary candidate.

The week was an accelerated version of Gingrich’s final month in Iowa, where he at one point carried a big lead and swore off negative campaigning. Then his foes drowned the state in anti-Gingrich ads, and he finished fourth.

“There’s not anybody I’ve known in politics who can up-and-down as well as Gingrich,” said Tom Slade, a former head of the Republican Party of Florida. “I think he got a fistful of money and I would bet you that he felt like that was, ‘Now I can start running a normal, natural campaign.’ And he can’t. That ain’t his gig.”

Slade said the debates — so crucial to Gingrich’s South Carolina surge — were his Florida downfall.

“He just put that set of skills in his hip pocket and started acting like a regular politician, and he really doesn’t do that very well,” Slade said.

Larry Sabato, the head of the University of Virginia Center for Politics, said a groundswell of establishment figures condemning Gingrich also took its toll. A series of GOP leaders aired their horror stories of Gingrich’s slash-and-burn style in Congress.

“The moment came after S.C., when Republicans realized for the first time that Newt could actually be the nominee,” Sabato wrote in an email. “Voters get serious at such moments. Plus, Gingrich’s legion of enemies stood up to be counted — or to mix metaphors, his large flock of vengeful chickens rushed home to roost.”

Gingrich has overcome such lulls in the past. On Friday his campaign released a tough new statewide television advertisement, in which an announcer asks: “What kind of man would mislead, distort, and deceive just to win an election? This man would. Mitt Romney.”

A Gingrich-allied Super PAC run by former aides also is rolling out a sequel to its “King of Bain” hit piece on Romney’s private equity firm.

The attacks only further inflame establishment Republicans who accuse Gingrich of giving ammunition to Democrats. At times, he seems to delight in the antipathy.

“There’s the Washington establishment sitting around in a frenzy, having coffee, lunch and cocktail hour talking about, ‘How do we stop Gingrich?’ ” he told reporters Thursday in Mount Dora.

The results of Tuesday’s vote are hard to predict, given the volatility of the polls and the fact that Florida has had early voting for weeks — some of it with Romney surging, some of it with Gingrich riding high.

The shift in the race has been evident in Hammond’s post-debate spin.

After Monday night’s event, Hammond said of his candidate: “It was his first debate as the front-runner.”

After Thursday’s debate, Hammond, asked who the front-runner was, replied: “I don’t think there is one.”