Newt Gingrich holds a commanding lead in his old home state, but his rivals are gaining just 25 days before Georgia’s Republican presidential primary, a new poll for The Atlanta Journal-Constitution shows.

The poll by Mason-Dixon Polling & Research shows Gingrich getting the support of 43 percent of voters likely to participate in the March 6 primary. Mitt Romney was second, followed by Rick Santorum and, in a distant fourth place, Ron Paul.

The poll, conducted Monday through Wednesday, likely does not reflect any surge that Santorum has enjoyed since he swept the vote in three states Tuesday night, said Mason-Dixon managing director Brad Coker. Coker said Santorum, the former U.S. senator from Pennsylvania, likely gained ground in Georgia after his sweep.

In Jackson, Gingrich supporter Stuart Longino said he has now begun to consider Santorum. Longino, 65, says he grew tired of the candidates’ bickering in South Carolina and Florida.

“Romney and Gingrich kind of tore each other up and it really turned a lot of people off,” Longino said. “I hated to see Gingrich seem vindictive — I don’t know if that’s the attitude we need in the big chair.”

The poll, conducted jointly for The Atlanta Journal-Constitution and the Georgia Newspaper Partnership, shows that Gingrich, a former U.S. House speaker and longtime Georgia congressman, has maintained his base of support here through the past several months, but has been unable to build on it.

A similar poll in December also showed Gingrich at 43 percent — but found Romney, the former Massachusetts governor, at 21 percent and Santorum at 1 percent. Last week Romney had improved to 29 percent, and Santorum to 12 percent.

Gingrich told The Atlanta Journal-Constitution the poll reflects his deep roots in the state.

“We have lots of volunteers and I have been active in the Georgia GOP since 1960 in Baker High School in Columbus, Ga.,” said Gingrich, who will campaign in the state next Friday and Saturday. “We hope to carry and expect to carry the state.”

The Romney campaign, however, notes that Gingrich’s support has stalled while Romney, who campaigned here Wednesday, has moved up.

“The more Georgia voters learn about Mitt Romney, the more they realize that he is exactly what our country needs right now,” Romney spokeswoman Amanda Henneberg said.

Coker reads the results differently.

He sees Gingrich holding his ground after a terrible stretch that saw him trounced in Florida.

The poll is “actually pretty good news for him,” Coker said. “Georgia is unique because this is home field for Newt. He still has a built-in advantage.”

Coker said if he were advising Romney he would urge the front-runner for the nomination to focus elsewhere and let Gingrich have Georgia.

“If Romney bypassed Georgia and put his emphasis on other places, nobody would think much of it if Newt won Georgia,” Coker said. “I don’t think Romney wants to carpet-bomb Newt in Georgia because he’s going to need Georgia in the fall. He pulled everything he had out of the magazine to win Florida. I don’t think he’s going to do the same thing to win Georgia.”

Mary Arrington, 67, of Pooler — on I-95 just inland from Savannah — is also now considering Santorum, although she was originally backing Romney. Santorum’s victories on Tuesday helped nudge her in his direction, Arrington said.

One thing is for sure, Arrington said: She will not be voting for the thrice-married Gingrich.

“I didn’t like him when he was in Georgia government,” Arrington said. “He’s a smart man, he just has some shady ways.”

The poll, however, found that while many Georgia Republicans have doubts about Gingrich’s integrity and his past, they’re still willing to vote for him. Asked to name the candidate with the most integrity, Santorum led with 34 percent, followed by Romney with 23 percent. Only 16 percent said Gingrich.

Forty-one percent, too, said they had a negative view of Gingrich’s marital issues. And yet, 57 percent said they had a favorable opinion of Gingrich overall, more than any other candidate.

Benjamin Hughes, a deputy sheriff in Dahlonega, said Gingrich’s competitors are using his past to bludgeon the candidate with the most experience and strongest positions.

“They’ve muddied the water on this guy so badly,” Hughes, 51, said. “If he can’t pull it off — he has to perform extremely well in the next two or three primaries, or he’s sunk.”

Coker, the pollster, said Hughes is representative of much of the state’s electorate, especially of voters in more rural parts of Georgia, where Gingrich runs strongest.

Gingrich, Coker said, “connects with the sort of rural white voters that are middle class, or blue-collar working-class voters. These are rural people, not suburban. They may be small-business owners, they may be farmers, they may just be plain-old working folks, but [to them] he’s the Georgia guy.”

Santorum supporters, meanwhile, believe that Gingrich still being below 50 percent in his home state is encouraging.

“If we keep Newt below 50, then these other candidates will get some delegates,” said Tim Echols, a member of the Georgia Public Service Commission who has endorsed Santorum. “With Santorum’s momentum coming off the trifecta of Tuesday, and the additional organization that our team is now really emboldened to do, the numbers will only get better.”

Echols is not sure Santorum has the time to overtake Gingrich in Georgia, but he believes his guy has a chance to pick up delegates anyway. The state’s 76 delegates will be doled out proportionally — some to the overall winner and shares to the candidate who wins the state’s different congressional districts.

Echols sees six or seven congressional districts in play.

“It’s all good news for Santorum right now, and it can only get better,” he said.

The good news for Santorum began to show up in other surveys. A Fox News national poll released Friday showed Santorum enjoyed a major boost from his wins this week, while a Georgia poll taken Thursday by Landmark Communications and Rosetta Stone Communications showed Santorum in second place with 26 percent, behind Gingrich’s 32. Romney had fallen to third, with 16 percent.

Audrey Haynes, a political scientist at the University of Georgia, said the Mason-Dixon poll shows real danger for Romney. His high negatives — 23 percent of respondents had an unfavorable opinion of him, second only to Paul’s 42 percent — speak to the conservative nature of the Georgia electorate, she said.

“Romney needs to mobilize moderate voters in Georgia and hope for a strong crossover vote from Democrats,” she said.

Staff writer Daniel Malloy contributed to this article.