Gingrich, the former House speaker, said he was infuriated by a barrage of attack ads that are blistering him on Florida TV stations ahead of Tuesday's GOP presidential primary. Most are funded by an outside organization backing Romney, but some are from Romney's own campaign. Unable to match Romney's money machine, Gingrich implored Florida Republicans to punish his chief rival for what Gingrich called callously dishonest ads.
"This is the desperate last stand of the old order," Gingrich told an outdoor crowd of more than 1,000 northwest of Orlando. "This is the kind of gall they have to think we're so stupid and we're so timid."
The nature and volume of the attack ads are similar to those that badly damaged Gingrich in Iowa a month ago.
"I think all the weight of his negative advertising and all the weight of his dishonesty has hurt us some," Gingrich said. But "I am not going to allow the moneyed interests that are buying those ads to come in here and to come into other states to misinform people and then to think we are too dumb to fight back."
Romney steered clear of his rival during a subsequent campaign appearance.
Gingrich later told reporters he decided to sharpen his criticisms after Romney's tax returns showed investments held in Cayman Island accounts, the government-backed mortgage company Freddie Mac and other entities.
"Here's a guy who owns Freddie Mac and Fannie Mae stock," Gingrich said. "He owns a Goldman Sachs subsidiary, which is foreclosing on Floridians. And on that front he decides to lie about my career? There's something about the hypocrisy that should make every American angry."
Romney has been hammering Gingrich for consulting work he performed for Freddie Mac and telling Florida voters that Gingrich was paid by a company that contributed to the state's poor housing market.
The acerbic remarks came three days after Gingrich took a much more moderate tone in a televised debate in Tampa, when Romney sharpened his own attacks. Gingrich strongly hinted he will be more aggressive in a CNN debate scheduled for Thursday night in Jacksonville.
Romney, meanwhile, toured a Jacksonville factory that is closing because of the economy before he addressed several hundred people gathered outside. He acknowledged that the live audience at Thursday's debate may be fairly raucous, a dynamic that seems to favor Gingrich and his populist, us-against-the-media and us-against-the-establishment style.
"There may be some give and take," Romney said. "That's always fun and entertaining, I know. If you all could get there, we'd love to see you all there cheering."
In his remarks, Romney criticized President Barack Obama and steered clear of Gingrich. He called Obama's administration a "Groundhog Day" presidency in which nothing gets better.
Polls suggest the Florida primary is close, coming 10 days after Gingrich beat Romney by 12 percentage points in South Carolina. Asked if he felt Florida was slipping toward Romney, Gingrich said, "I feel that it's useful for people to look at the totality of his record and ask yourself, 'How can a guy who literally owns stock in a Goldman Sachs investment fund that forecloses on Floridians run the ads he's been running?'"
Goldman Sachs employees and their families contributed $367,200 to Romney's campaign through Sept. 30, his largest source of campaign contributions, according to the Center for Responsive Politics.
Former Pennsylvania Sen. Rick Santorum and Texas Rep. Ron Paul also were participating in Thursday's debate, the final one before the GOP presidential primary in Florida on Tuesday. But both candidates have set their sights elsewhere and have largely stayed away from the Romney-Gingrich drama.
Whoever wins Florida will score something no one has yet claimed in a tumultuous primary season: a second victory. The first three contests have been won by three different candidates. Only Paul has yet to score a win.
The hits for Romney and Gingrich were coming from many directions.
The "super" political action committees backing them have spent more than $10 million combined on ads to date in Florida, far more than their respective campaigns. The Romney-leaning Restore Our Future has spent $8.8 million in ads as of late Tuesday, bringing to $14 million the total spent on ads supporting Romney in the state. That doesn't include money already spent on radio and Internet advertising.
As of late Tuesday, the Gingrich-backing Winning Our Future had booked $1.8 million in television ads in Florida, a check made possible by a new donation from Miriam Adelson. She and her husband, Sheldon, this month gave $5 million apiece to the group, which supports Gingrich but legally must remain independent.
Santorum, meanwhile, seemed to be recognizing that he stood almost no chance of winning Florida. He and his advisers planned no advertising in the state and instead were focused on raising money and calling potential supporters in upcoming states. He all but gave up trying to woo a network of pastors and was scaling back his schedule in Florida.
Chuck Laudner, an influential adviser who helped Santorum score an upset victory in the Iowa caucuses, was returning to the Midwest to start piecing together coalitions in Missouri and Minnesota. Both states have media markets that overlap with Iowa, where Santorum proved to be the big story.
Paul, virtually absent from Florida except for appearances built around the debates, was concentrating instead on caucus states where his loyal backers can carry a louder voice.