Newt Gingrich acknowledged his slide in the Florida polls on Sunday, saying he had slipped under the “sheer weight of [Mitt] Romney’s money and the negativity of his campaign.”

Gingrich, the former House Speaker, has fallen well behind Romney in the critical Sunshine state primary two days before the vote, as new poll show him behind by double-digits.

Gingrich did not try to dispute the latest numbers in television appearances on Sunday, but in a subtle push for conservatives to coalesce, he noted that he and former Pennsylvania Sen. Rick Santorum (R) were jointly beating Romney and that Romney could be defeated if conservatives did not split the vote.

Romney “has a basic policy of carpet-bombing his opponent,” Gingrich said on “Fox News Sunday” in explaining his slide. “He doesn’t try to build up Mitt Romney, he just tries to tear down whoever he’s running against. And it has an effect. We’re in a very tough campaign down here.”

Gingrich accused Romney of running “factually false” ads while defending his own negative ads on the merits.

The former Speaker also deepened his attack on Romney from the right. Where Gingrich had repeatedly referred to Romney as a “Massachusetts moderate,” on Sunday he called him a “Massachusetts liberal.”

Gingrich also denounced Romney for being “fundamentally dishonest,” but when pressed on both Fox and ABC, he stopped a breath short of declaring Romney unfit for the presidency.

“You cannot be president of the United States if you cannot be honest and candid with the American people,” Gingrich said. “That is a very serious problem.”

On CBS’s Face The Nation, Gingrich repeated his attack that Romney has been dishonest.

“He came into the debate prepared to say things that are false,” said Gingrich. “I think someone who is running for the president has a unique requirement to be honest because the only way you lead the American people is by having them believe in you.”

Gingrich also took aim on Sunday at members of the Republican establishment who have endorsed Romney and have increasingly warned in recent days against nominating Gingrich for the presidency. Chief among those was Bob Dole, the former Senate majority leader and 1996 GOP standard-bearer who released a blistering statement last week criticizing Gingrich.

On Fox News Sunday, Gingrich called Dole “a moderate” and noted his loss in the 1996 general election against President Clinton. “We’ve tried a moderate in 1996, and he couldn’t debate Bill ClintonWilliam (Bill) Jefferson ClintonTrump’s first year in office was the year of the woman Can a president be impeached for non-criminal conduct? Dems search for winning playbook MORE effectively and he lost,” Gingrich said. “We tried a moderate in 2008. He couldn’t debate Barack ObamaBarack Hussein ObamaMcCarthy: ‘No deadline on DACA’ Democrats will need to explain if they shut government down over illegal immigration Trump’s first year in office was the year of the woman MORE effectively, and we lost,” he added, referring to Sen. John McCainJohn Sidney McCainMcCain rips Trump for attacks on press NSA spying program overcomes key Senate hurdle Meghan McCain says her father regrets opposition to MLK Day MORE (R-Ariz.), who has endorsed Romney.

“Do I ruffle feathers? You betcha,” Gingrich said. “This campaign is precisely about challenging the establishment. I think Senator Dole is a quintessential part of the establishment.”

Gingrich on Sunday also vowed to stay in the race beyond Florida and said Romney was not close to rallying a majority of Republicans to his campaign.

“The fact is this race is going to go on,” he said on ABC’s “This Week.” “This is going to go on all the way to the convention.”

He seemed to suggest, at least implicitly, that his best chance at winning the nomination would be if Santorum dropped out of the race and conservatives united behind his candidacy. “We’re splitting the conservative vote,” Gingrich had said on Fox.

Kevin Bogardus contributed.

This story has been updated.