"This is a long way from being over," he said, as he shook hands and took pictures with voters after they cast ballots at the First Baptist Church of Windermere. "I'd say June or July unless Romney drops out earlier."
He dismissed the political observers who say that his candidacy is over if he loses Florida's 50 delegates.
"The same people who said I was dead in June, or the people who said I was dead in Iowa, those people?" Gingrich said. "They're about as accurate as they have been the last two times they were wrong."
Gingrich came into Florida surging off his come-from-behind win in South Carolina, but his support has eroded after two lackluster debate performances here and a multimillion-dollar barrage of attack ads by Romney and his supporters.
"It's particularly a challenge when the governor's campaign is so methodically dishonest," Gingrich said, accompanied by wife Callista and Michael Reagan, the son of the late president who has endorsed the former House speaker.
He urged undecided voters to support him because he would offer the greatest contrast with President Obama, and pointed to the healthcare reform law Romney created when he was governor of Massachusetts.
"If they want to beat Obama, I believe a conservative has a much better chance than somebody who offered Romneycare, which is the forerunner to Obamacare," he said.
Jeannie Stephan, 43, votes at another location but visited the church because she heard Gingrich was going to be there. The substitute teacher said she is leaning toward Gingrich because she likes his experience as House speaker in the 1990s, but was concerned about electability in the general election.
"I think Newt's more conservative," she said. "I'm most concerned about who can beat Barack Obama. Everyone I talk to says Romney has a better chance."
But she is displeased by attack ads launched by Romney and his supporters. In recent days, she has been receiving a half-dozen phone calls a day and can't turn on the television or the radio without being inundated.
"The negativity of the Romney ads – it's too much," she said. "It's a real turnoff."
Anne Easterling, 54, was giddy as she shook hands with Gingrich after casting her ballot for him.
"I just want to let you know how much I appreciate your voicing what all of us are thinking," she told him. "It's such a joy to listen to you during debates and it's a real honor to meet you."
The Web developer said that while she appreciates Romney's business background, she believes Gingrich has more zeal for the values and principles on which the nation was founded.
"Passion is what's going to connect with people and can we inflame in people the same passion that Obama supporters have? I think Newt can do that," Easterling said.
But others were less enchanted by Gingrich, particularly his ambitious and, some would argue, fanciful ideas, such as having a colony on the moon by 2020.
"If he makes it all the way, I'd rather vote for Obama. He's out of left field," said Raj Patel, 37, after casting a ballot for Romney.