Newt Gingrich stirred a huge tea party crowd in this central Florida town Thursday by accusing Mitt Romney and the Republican establishment of slinging “mud” and “junk” because “they’re against change in Washington.”

Using the word “stupid” at least a dozen times to describe how Romney views voters, Gingrich said his rival’s negative ads about Gingrich’s consulting work for the mortgage giant Freddie Mac are dishonest and hypocritical — and represent a desperate attempt by the establishment to block Gingrich’s campaign.

“Well, I’m here as a citizen, and I frankly don’t care what the Washington establishment thinks of me because I intend to change them,” Gingrich said, prompting cheers and chants of “Newt! Newt! Newt!” from a crowd that the local sheriff’s department estimated at 1,500.

“That’s true. We have to ultimately focus on beating Barack Obama, but 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.”

In a mocking release, Romney’s campaign labeled Gingrich “Dr. Newt and Mr. Hyde” — the latter, they said, showed up at the Mount Dora event Thursday morning — and accused him of leading an “Occupy Mount Dora” rally against free enterprise. Composed almost entirely of quotes from news accounts of the event and other Gingrich attacks on Romney’s wealth, the release included just one quote from a Romney staffer: “Wow,” said communications director Gail Gitcho.

Gingrich’s tone reflected how high the stakes are in Florida just four days ahead of the Republican primary here. Hoping to ride a wave of momentum from his huge win in South Carolina last weekend, Gingrich echoed the anger and edge that he displayed in the days leading up to the Iowa caucuses in early January, when a pro-Romney group was hammering him with millions of dollars in negative ads — and where he finished a distant fourth.

But if Gingrich’s anger reflected the challenges of a moment when he is again under assault, it also reflected a potential opportunity to — again — turn the story around. In Florida this week, Gingrich has demonstrated a strong network of tea party support, where his efforts to cast Romney as the insider and himself as the insurgent have played well with huge crowds. He will have another moment to do so Thursday in a televised debate in Jacksonville, the final such event before Tuesday’s primary.

The moment is challenging for Romney, too, whose campaign is trying to regain momentum lost in South Carolina and has stepped up the intensity of its attacks on Gingrich’s work as a Washington consultant. Romney has also begun sending out a team of high-profile surrogates to shadow Gingrich at his public events and provide real-time rebuttals to the press.

“It’s laughable for him to cast himself as an outsider,” said U.S. Rep. Jason Chaffetz (R-Utah), who along with fellow Romney supporters Rep. Connie Mack (R-Fla.) and Rep. Mary Bono Mack (R-Calif.) trailed Gingrich across Florida on Thursday. “He could not get elected speaker of the House right now. He is an unreliable leader who was pushed out the door. He has more scandal surrounding his personal life and his professional life than we should have in our nominee.”

There is some danger for Gingrich in his guns-blazing approach, observers said. South Carolina voters appeared to love Gingrich on the attack, but if he overdoes it, Florida voters might come to believe Gingrich is too bombastic and bullying — as Romney supporters have charged — to be a smart choice to take on Obama in the general election.

“He’s got great ideas, but at times he’s erratic. He’s emotional. And he’s flamboyant,” Connie Potter, 72, a retired nurse, said of Gingrich. She voted early for Romney and attended a Jacksonville event for him Thursday. “Flamboyant might be fun and exciting, but it’s not what I’m looking for in a president. Romney will make the same decisions, but will do it in a more stable and mature way.”

Also Thursday, former congressman Jeb Bradley (N.H.) described how Gingrich worked to persuade him and other Republican lawmakers in 2003 to pass a new Medicare prescription drug benefit.

“I didn’t know at the time that he had a stable full of health-care clients — not that that would have mattered. There’s nothing wrong with lobbying. But when you’re running for president of the United States, you’re supposed to be honest and forthright about what you are and what your career is,” Bradley said.

Bradley said it was “pious baloney” — Gingrich’s own now famous phrase about Romney — for Gingrich to suggest he’s not been a lobbyist.

Such critiques don’t seem to be blunting the enthusiasm of tea party-friendly Republicans, who turned out in force Thursday for Gingrich at a lakeside green in Mount Dora after finally committing to rallying around the former House speaker in a conference call Sunday.

Gingrich drew crowds of 2,500 in Sarasota and 5,000 to Naples earlier this week; he also just in the past few days has consolidated the support of 42 different tea party groups across the state — a development that allowed Thursday’s rally, which was still uncertain a few days ago, to proceed.

“Remember: The Republican establishment is just as much as an establishment as the Democratic establishment, and they are just as determined to stop us,” Gingrich said at Thursday’s rally, again prompting cheers and yells from a crowd dotted with slogans such as “Don’t Tread on Me” and “No-Bama.”

“Make no bones about it,” Gingrich continued. “This is a campaign for the very nature of the Republican Party and the very opportunity for a citizen conservatism to defeat the power of money and to prove that people matter more than Wall Street and that people matter more than all the big companies that are pouring the cash in to run the ads that are false.”

Jose Mallea, Gingrich’s Florida director and the former campaign manager for one of the tea party’s earliest stars, Florida Sen. Marco Rubio, said Texas Gov. Rick Perry’s departure from the race and Santorum’s poor showing in South Carolina contributed to their decision.

“The tea party was still fractured last week,” Mallea said. “Some of them were with Perry, some of them were with Santorum. Not many of them were with Romney, but they weren’t sure where they were going to go.”

Rubio has remained neutral in the race, but his many of his supporters have joined Gingrich. Rubio was not happy with an advertisement Gingrich has been running against Romney in which he characterizes the former Massachusetts governor as “anti-immigrant.”

But sources close to both Rubio and Gingrich said the two had a long and amicable conversation Wednesday. In addition, a source with knowledge of both operations said Rubio has been inundated with calls from grass-roots supporters who weren’t happy that he appeared to be criticizing Gingrich.