Following an onslaught of attacks in last week's debates and on the Florida airwaves, Newt Gingrich amped up his criticism of frontrunner Mitt Romney this morning, aiming his arrows directly at Romney's character and calling him "fundamentally dishonest."

"I am saying that he would not be where he is today, the debates this week wouldn't have been where they were, if he had told the truth," Gingrich told me this morning on "This Week." "And I think that's a very serious problem for somebody."

Gingrich said Romney has run a "campaign of vilification" that is based on "factually false" claims and "carpet-bombing with negative ads." When I asked the former speaker if Romney had the character to be president, Gingrich said "it is a very serious problem."

"You cannot be president of the United States if you cannot be honest and candid with the American people," Gingrich told me.

Romney dominated Thursday's debate and devoted a hefty chunk of the two-hour event to attacking Gingrich's immigration stance, the work he did for mortgage giant Freddie Mac, and the ethics investigation of Gingrich while he was in the House.

On Sunday, Gingrich said such attacks were "blatantly dishonest" and based on "totally phony history, which [Romney] maniacally continues to repeat."

"I'm standing next to a guy who is the most blatantly dishonest answers I can remember in any presidential race in - in my lifetime," Gingrich said. "I don't know how you debate a person with civility if they're prepared to say things that are just plain factually false."

Gingrich, who trails Romney by 15 percentage points in the latest Florida poll, released today by NBC News/Marist, said that while Romney may come out ahead in Florida, the race is far from over.

Gingrich said he expects the campaign to "go on all the way to the convention" because Romney is "not going to be anywhere near a majority by April."

He blamed Romney's lead in the Sunshine State on the former governor's deluge of negative ads. Romney and his supporting Super PAC have dumped $8.2 million into Florida ads - nearly four times as much as Gingrich and the pro-Gingrich Super PAC have spent.

"It's only when he can mass money to focus on carpet-bombing with negative ads that he gains any traction at all," Gingrich said.

Florida Republicans head to the polls on Tuesday in the largest state yet to vote this nominating season. Fifty delegates are up for grabs in the Sunshine State.