In a campaign season dominated by million-dollar infusions to Super PACs, carpet-bombing TV ads and wall-to-wall GOP debates, it finally comes down to this:

A mom and her two daughters, knocking on the doors of strangers; a veteran of the days when Republicans were a rarity in Georgia, dialing, dialing and dialing some more; a Florida stalwart, driving here to impart lessons learned in that state’s primary; a bleary-eyed volunteer, fresh off a plane from India, where she got a campaign slogan inked on her hands.

Whether it’s the well-oiled machine of former Massachusetts Gov. Mitt Romney or the do-it-yourself campaign of Texas Rep. Ron Paul, the faith-infused effort of former Pennsylvania Sen. Rick Santorum, or the Georgia-inflected campaign of onetime Georgia Rep. Newt Gingrich, these are the days when the campaign rubber meets the road, when the ground game matters.

NEWT GINGRICH

Friday, at a makeshift headquarters in Marietta — in Gingrich’s old Cobb County stomping grounds — four volunteers worked the phones for the former House speaker.

Barefoot in workout clothes, Liz Bozzuto ticked through her calls of likely Republican voters. Years ago, she said, she served on a task force in Gingrich’s 6th congressional district and said she’s been a fan ever since.

Kevin Harris, Gingrich’s Georgia coordinator, said Georgians have rallied strongly to the state’s GOP favorite son. At one event in Dalton last week, he said, the campaign signed on 360 volunteers.

“This is home state and the grass-roots game is very strong,” Harris said.

The pro-Gingrich Super PAC “Winning Our Future” is also spending in the state, widely considered a must-win for Gingrich, who has trailed Romney and Santorum in many states heading into Super Tuesday. The group is running two television ads aimed at Romney and several radio ads targeted at conservative listeners.

The campaign has the feel of a homegrown affair. Jackie Gingrich Cushman appears on the stump for her dad. Gingrich’s top supporter in the state, Gov. Nathan Deal, is an old friend from their years together in the U.S. House. And the former speaker is tapping some of the same Georgia GOP stalwarts whose careers he helped launch when the state’s now-dominant Republican Party was a scrappy upstart.

Gingrich has led his own ground game in Georgia, spending far more time here than his GOP rivals. He rumbled through the state last week on a bus tour from Dalton to Valdosta, where he has reminded Georgians about his two decades on Capitol Hill representing the state. One stop was at the University of West Georgia in Carrollton, where he waxed nostalgic about his time there teaching history.

He also has 12 paid staffers organizing get-out-the-vote efforts, as well as a small army of volunteers who have been manning phone banks, traveling door to door and distributing yard signs.

It can be thankless work, stuffing campaign literature in screen doors or making your pitch to an answering machine because no one answers. But sometimes the message connects.

“Well, bless you,” Bozzuto said as she reached one voter who said she’d voted early for Gingrich. “I know he appreciates your support.”

RON PAUL

On Saturday, on a busy street corner in north DeKalb County, the Paul ground game was in full swing. Two dozen adherents to Paul’s non-interventionist, libertarian-leaning philosophy, waved signs, hailed passing motorists and handed out literature, helping to keep their candidate’s name afloat.

For two weeks, Sam Moore, 35, a Canton resident and Georgia Tech graduate, has stood on a Cherokee County street corner during evening rush hour, holding a Ron Paul sign and handing out literature. On Saturday, he called up friends in DeKalb County and invited himself to a sign-waving in their neighborhood, at the corner of North Druid Hills and Briarcliff roads.

Bringing a trunk-full of signs to the event (he’s spent $700 buying campaign materials), Moore and his wife, Galina, elicited a few friendly honks and the occasional shout of dissent. “There’s finally somebody worth voting for, so it’s my moral obligation to do something,” he said.

Since Paul has just one full-time Georgia staffer, and their candidate won’t be visiting Georgia, concentrating instead on states that hold caucuses, the volunteers take matters into their own hands. They communicate through Meetup.com, buy their own yard signs, print their own brochures, and create their own phone banks at home, using software and lists provided by the national campaign.

“You are the campaign,” said Douglas White, 44, of Pompano Beach, Fla., an automobile mechanic, who drove north to participate in a Marietta Ron Paul rally last weekend after Paul’s dismal showing in Florida. “I brought my learning curve up here,” White said.

David Sarosi, 48, a process engineer from Tucker, promoted Paul’s monetary policy with a home-made placard emblazoned “In Gold We Trust.”

“If we’re going to be effective,” he said, “we have to be effective at a local level.”

MITT ROMNEY

Ruth Malhotra, a Romney volunteer, took a red-eye flight from New Delhi, India, to make it back to Atlanta on Thursday in time for an appearance by the candidate’s wife, Ann. As a sign of her support, Malhotra had the words “Smitten Mitten” inked on her hands with henna while she was in India.

“It’s really exciting to see so much campaigning in Georgia, even though it’s Newt Gingrich’s home state,” said Malhotra, a researcher for the academic nonprofit Middle East Forum who first worked for Romney in his unsuccessful bid for the 2008 nomination.

“I think Mitt Romney has a very scholarly perspective,” she said, but he still focuses on real-life solutions to challenges, whether it’s in business or with the Olympics in Salt Lake City.”

She and other Romney supporters got another boost Sunday when Romney himself made an appearance in the state. The former Massachusetts governor swung through Georgia to host a pancake brunch at Brookwood High School in Snellville, before heading to Knoxville, Tenn., for an evening rally.

Debbie Moscato, president of the Buckhead Republican Women and Romney volunteer, said she’s glued to the election news while urging people to vote for her candidate.

“Mitt is my rock star,” said Moscato, who attended both Ann and Mitt Romney’s respective events this week.

Eric Tanenblatt, a managing director at the McKenna Long law firm and top Romney ally in Georgia, said the campaign headquarters started operating about a week ago in Buckhead. Volunteers are working in shifts to call likely voters and knock on doors across the state, he said.

“The last 72 hours of a campaign are the most critical, and so that is what is happening right now,” he said.

RICK SANTORUM

Clipboard in hand, a stack of Santorum signs in his pickup truck, Chris McClurg set out Saturday morning to knock on doors in Suwanee and Sugar Hill.

The clipboard held a list of dos and don’ts. (Do offer information; don’t debate.) He also sent some visual cues, wearing an Army veteran hat and a button that said: “Guns Save Lives.”

McClurg said his team of a handful of volunteers canvassed more than 700 homes over the past two weekends.

A local attorney, he knows from his experience with juries that you don’t try to sell people too hard. “Hi, I’m Chris McClurg, and I live over in Sugar Hill,” he said when someone answered his knock. “I’m supporting Rick Santorum. Do you plan on voting in the primaries?”

He walked briskly, with a purpose, through the Gwinnett County neighborhood that has lots of two-car garages and cul-de-sacs and Republican voters, and he made sure to spend no more than three or four minutes per home.

“Voter contact is the thing,” said state field director Kathy Hildebrand. “I want people knocking on doors, handing out cards and waving signs.”

Working with McClurg was volunteer Annie Valenty of Suwanee. He worked one side of the street and she the other. She was joined by her two daughters, Emma, 8, and Katie, 9. Valenty wanted to teach the girls to get involved in their community.

Some people would only talk through a closed door. Some cracked the door a bit and stuck out an arm to get some literature. But John Casey greeted Valenty and the girls warmly as they talked of Santorum.

“That’s who I’m voting for,” Casey told them.

Next thing, he was letting them plant a sign in his front yard. He liked the fact that someone would take the time to contact him personally.

“It tells me he (Santorum) has family values,” Casey said. “There’s proof right there: a mother and her two girls.”

-- Staff writers Bo Emerson, Victoria Loe Hicks, Katie Leslie, Shannon McCaffrey and Craig Schneider contributed to this report.