ORLANDO, Fla. -- After storming into Florida with a head of steam from a surprising win last Saturday in South Carolina, Newt Gingrich's support has waned and polls suggest he could lose Florida's primary Tuesday, perhaps by a wide margin.
Mr. Gingrich has run into a newly energized, hard-hitting opponent in Mitt Romney, a TV-dominated mega-state where he can't afford to play, and a diverse state in which transplanted Northeasterners and Midwesterners aren't as welcoming to his message.
At the same time, the party establishment is rallying to stop him.
And after Florida, there will be a weeks-long stretch with no TV debates, once the lifeblood of Mr. Gingrich's cash-poor campaign.
"Gingrich's momentum from his South Carolina victory appears to have stalled and ... Romney seems to be pulling away in Florida," said Peter A. Brown, assistant director of the Quinnipiac University Polling Institute.
Polls punctuated the turnaround. A Quinnipiac poll Friday found Mr. Romney with the support of 38 percent of likely Florida primary voters, Mr. Gingrich with 29 percent, Rep. Ron Paul of Texas with 14 percent, and former Sen. Rick Santorum of Pennsylvania with 12 percent.
Mr. Paul made clear his intention to skip Florida in favor of smaller states that cost less to campaign. Friday, he began a two-day visit to Maine.
With 3 in 10 likely voters saying they might change their minds, it's possible Mr. Gingrich could gain again.
"With the debates now over, Gingrich will need some other way to reverse the tide that appears to be going against him," Mr. Brown said.
Trailing in polls, Mr. Santorum headed home to Pennsylvania for a short visit, effectively turning his back on the Florida primary.
Campaign officials said Mr. Santorum will attend a fund-raiser, prepare his tax returns for release, and hold a news conference in West Chester, Pa.
Mr. Santorum, a devout Catholic who has tried to position himself as the social conservative alternative to Mr. Romney, dismissed speculation he might quit after Florida. "I will make an absolute statement; there hasn't been a discussion and not even approaching a discussion to discuss a discussion as to whether to get out of this race," he told CNN.
He plans to return to Florida to campaign this weekend but has been unable to compete with Mr. Romney and Mr. Gingrich in spending on TV ads in Florida.
Mr. Santorum is looking beyond Tuesday's primary.
"We're focused on Nevada and Colorado, where we think there are more opportunities for us," he said on Thursday after giving a speech on "Faith, Family, and Freedom," to about 200 college students at Florida State University. "We're going to stay in this race for the long haul."
Mr. Gingrich began Friday by launching a tough TV ad accusing Mr. Romney of distortions and deceptions "just to win an election."
In an interview with the Washington Post, Mr. Gingrich said he was stunned by Mr. Romney's debate performance Thursday, which he characterized as "the most blatantly dishonest performance by a presidential candidate I've ever seen."
Mr. Gingrich has struggled to raise money and build field organizations in some of the critical primary states, and it is unclear how he will be able to continue his campaign if he loses in Florida.
Several factors have combined in Florida against Mr. Gingrich, a former speaker of the House of Representatives.
First, Mr. Romney has fought back hard.
The ex-Massachusetts governor came out swinging against Mr. Gingrich in a Florida debate Monday, then did it again Thursday. He slammed him for airing an ad calling Mr. Romney anti-immigrant, ripped anew Mr. Gingrich's paid work for troubled housing agency Freddie Mac, and ridiculed his idea to colonize the moon.
Second, Mr. Romney can could afford to advertise heavily, the only candidate with the means to do so in a state with 10 media markets.
More important, the debates and TV ads found an audience in Florida different from that in South Carolina.
"There are a lot of transplants from the Midwest or Northeast who can relate to Romney's style of politics. They're country-club Republicans," said Brad Coker, an Florida-based pollster. "The evangelical vote is much more watered-down."
Mr. Gingrich faced another head wind as his South Carolina win turned him from second-tier candidate into possible nominee: A wave of voices spoke up against him.
"It is now time to take a stand before it is too late," said former Sen. Bob Dole of Kansas, the party's presidential nominee in 1996 and vice presidential nominee in 1976. "If Gingrich is the nominee, it will have an adverse impact on Republican candidates running for county, state, and federal offices."
As speaker from 1995 through 1998, Mr. Gingrich "had a new idea every minute and most of them were off the wall," Mr. Dole wrote. He said he struggled against Democrats' TV attacks in his 1996 campaign, "and in every one of them, Newt was in the ad."
Mr. Gingrich has reacted unevenly to the accusations, sometimes denouncing them, other times wearing them like a badge of honor.
"The Republican establishment is just as much as an establishment as the Democratic establishment, and they are just as determined to stop us," he told a Tea Party rally Thursday in Florida.
Several conservative pundits also turned up the heat.
Conservative columnist Ann Coulter accused Mr. Gingrich of "hotheaded arrogance."
George Will questioned giving him control of nuclear weapons.
Matt Drudge, whose Drudge Report is the mega-must-read Web site for conservatives, has been blaring anti-Gingrich headlines.
After Florida, the campaign heads into a stretch of caucuses -- Nevada, Colorado, Minnesota, and Maine -- in which organization is key, there aren't any televised debates and Mr. Gingrich may not be able to compete as well.
He won't feel the warmth of TV lights on a debate stage until Feb. 22 in Arizona.