TAMPA, Fla. -- Meet Newt Gingrich, the human Roman Candle.

Gingrich and Mitt Romney on Monday staggered to the end of a brutal week of campaigning in Florida, one in which they took increasingly nasty and personal shots at one another. But the day marked a new level of angry and relentless attacks on Romney by Gingrich, the former House speaker from Georgia.

From morning until the last of five events at the end of the day, Gingrich branded Romney a liar and cheat, accusing him of suppressing religious liberty and trying to "buy the election."

The strain of the nastiness showed on both men. Romney's voice was hoarse as he spoke at his last of three events, in front of a few thousand people at The Villages, a massive retirement community 90 minutes northeast of Tampa. But in a sign of growing confidence and looseness as a candidate, Romney led the crowd in singing "America the Beautiful," a tune he has mentioned on the campaign trail all month without breaking into song.

Romney didn't mention Gingrich by name at his last event, after mocking and dismissing him earlier in the day.

Gingrich, on the other hand, launched himself into the Romney juggernaut with a level of fury and desperation certain to produce uneasiness in the GOP for its poisonous tone. Gingrich has vowed to carry his candidacy all the way to the GOP convention, but his actions Monday bore a wildness that could call his campaign's longevity into doubt.

Gingrich continued to harp on a charge that Romney, during his time as Massachusetts governor, vetoed funds to expand the provision of kosher food for Bay State retirees. Gingrich said Romney has a “lack of concern for religious liberty."

"Romney cut off kosher food to elderly Jews on Medicare," Gingrich said, stretching the truth. And Gingrich also hit Romney for a 2005 decision as governor to require Roman Catholic hospitals to provide emergency contraception, which many Catholics believe is a form of abortion, to rape victims.

"You want a war on the Catholic church by Obama? Guess what: Romney refused to allow Catholic hospitals to have conscience in their dealing with certain circumstances," Gingrich said.

Having called Romney "pro-abortion, pro-gun control, pro-tax increase" on Sunday, Gingrich added the title "pro-gay rights" on Monday, in an acidic interview with Fox News. He rewound his last few days of attacks, combining all of his insults and all his vitriol into a string of remarkable assaults on Romney.

"The conservative movement is not going to sit back and say, 'Oh yes, let's let Wall Street and Mitt Romney buy the election,'" Gingrich said. "So you're going to see a real grassroots fight. It will be people power vs. Goldman Sachs and Mitt Romney."

Gingrich's campaign began the day by sending out a press release noting that Romney has received $367,000 in campaign contributions from Goldman Sachs, the New York investment bank.

"Goldman Sachs received $10 billion in emergency loans and bailouts from the Federal Reserve during the Wall Street bailout," wrote Gingrich's communications director Joe DeSantis. "This raises the question: Are Mitt Romney's dishonest attack ads against Speaker Gingrich being indirectly funded by the US taxpayer while Governor Romney uses shady accounting gimmicks to avoid paying his fair share of taxes?"

Gingrich went after discrepancies on Romney's tax returns as well.

"How can a guy who's a great manager not file 23 foreign holdings last year when he filed?" Gingrich asked reporters in an unannounced press scrum. "There are a lot of pieces of Mitt Romney that don't hold up once you start looking at them honestly."

From a stage a few minutes later, Gingrich raged against the Romney campaign's systematic dismantling of his momentum in the week since his win in South Carolina 10 days ago.

"The New York Times has now reported that the Sunday after South Carolina, the Romney team got together and said, 'Look, we need to destroy Gingrich or we can't win.' So they've now spent $17.5 million on falsehoods," Gingrich said, overstating by $2 million the amount that Romney's campaign and a super PAC supporting him have spent. Nonetheless, Gingrich and his allies have been outspent 4 to 1.

A spokesman for a super PAC supporting Gingrich, Winning Our Future, amplified Gingrich's attacks with vicious jabs at Romney.

"Romney has proved to be a disgraceful and despicable candidate. He has no character," Rick Tyler, a former Gingrich aide, said of Romney.

Romney, who has criticized Gingrich this week directly, did not engage him head-on, dismissing Gingrich as desperate.

"I know the speaker's not real happy, Speaker Gingrich," Romney told a crowd of hundreds at a park in Dunedin. "He's not feeling very excited these days. I know, it's sad, right? He's flailing around trying to go after me for one thing or the other and you just watch it and you shake your head."

Gingrich tried to fight off the impression he was headed for a drubbing Tuesday.

"The polls are all over the place. We just got word of a brand new poll that came out about an hour ago that says we're now tied 35-35," Gingrich told a crowd of about 200 in a Tampa air hangar.

The crowd went nuts. The problem was, the poll was nearly a week old, not an hour. It was conducted last Monday to Wednesday, and released on Friday. Every other poll during the last week has shown Romney far ahead of Gingrich, many by double-digits.

Gingrich has vowed to stay in the race all the way to August, and to take his fight against Romney to the Republican convention, in Tampa from Aug. 27 to Aug. 30.

Elise Foley contributed reporting from Dunedin.