For Newt Gingrich, persistence has its rewards. Four months after early missteps nearly doomed his presidential aspirations, he has defied expectations, crept up in the polls and become a draw on the campaign trail.

His tenacity has also been a boon in other ways. It has bolstered his personal brand as the Republican Party’s venerated idea man, who on Thursday released a revamped version of his 1994 “Contract With America.” It has provided a platform to promote his vast catalogue of books and documentaries. It has even helped his wife, Callista, whose new children’s book recently shot to No. 3 on Amazon’s list of bestsellers.

Federal election law allows candidates to use small portions of their campaign money to promote their books. But the cross-promotion, and the impression that Gingrich is not campaigning heavily, has prompted speculation that his efforts are motivated by something other than a desire to become president.

That was even the subject of a “Saturday Night Live” parody of a recent Republican debate, with the Gingrich character acknowledging his lack of interest in the campaign and walking offstage.

Gingrich says he has done nothing improper by intertwining his campaign with his promotional activities, and during his remarks at an event in Doylestown this week he emphasized that he is committed to his presidential campaign — but not before giving a plug to his wife’s book, “Sweet Land of Liberty,” featuring Ellis the Elephant.

“I just want to say on behalf of Callista, you should take a bow in a second,” he joked during his campaign remarks at the Moose Lodge, where he had attracted a standing-room-only crowd.

The success of Callista Gingrich’s book, he said, is evidence that “there is such a hunger among parents and grandparents and aunts and uncles for children to learn about America, and they know that patriotism in its traditional form is simply not being taught in the schools.”

In an interview, Gingrich said he is uniquely qualified to be president because of his two decades as a member of Congress, his four years as House speaker, his work outside government and the scale of the challenges the country faces.

“I’m the only one running who worked with Reagan,” he said. “I’m the only person running who worked with [former British prime minister Margaret] Thatcher. I have a pretty good sense of how you solve these things. I’ve actually done it in Washington.”

The scale of his “21st Century Contract With America” is “breathtaking,” he added, “and I’m prepared to spend the next 10 years of my life implementing it.”

The new 26-page contract — which his aides said he typed on his BlackBerry — includes proposals to replace last year’s health-care overhaul with a more “pro-market” version, simplify the tax code to reduce the burden on corporations and individuals, and revamp Social Security to allow young people to save some of their contributions in private accounts.

R.C. Hammond, a Gingrich spokesman, said the campaign has recovered since staff members left en masse in June after complaining that the former House speaker didn’t appear serious about running for president. The campaign has about 15 paid workers, and offices in Florida, Virginia and Georgia. Gingrich will have spent 24 out of 30 days in September on the road stumping and expects to ramp up his efforts, Hammond said.

The exodus of the aides was but one stumble early in the campaign. He alienated many Republicans when he called House Budget Chairman Paul Ryan’s budget plan “right-wing social engineering,” a comment he later retracted. He struggled to explain how he and his wife had carried as much as $500,000 in debt on a revolving charge account at Tiffany. And his last finance report showed that his campaign was $1 million in debt.

But his fortunes shifted with the debates, Gingrich said. Indeed, many of those who came to this tea-party-sponsored town hall meeting said they were impressed by Gingrich’s performances and won over by his confident demeanor, his depth of knowledge and his clear positions.

All of that comes easy for him, his staff said.

“Debate prep for Newt is a Diet Coke,” Hammond said.

Several audience members said they appreciated his chiding of the debate moderators for pitting the candidates against one another asking “Mickey Mouse” questions.

“When they did allow him to speak, he made so much damn sense I couldn’t even believe it,” said Judy Underwood, 54, a retiree from Bucks County who said she is undecided in the race.

The next campaign finance disclosure will show that some of Gingrich’s debt has been paid, that the campaign is operating within its budget and that there has been a rebound in online and grass-roots fundraising, Hammond said. A recent CNN/ORC International Poll found that Gingrich was the third choice among Republican voters nationwide, after Texas Gov. Rick Perry and former Massachusetts governor Mitt Romney, with 11 percent of the vote.

Still, Gingrich as much as acknowledged his challenges. “Either we’re going to organize a very large grass-roots movement and win the nomination, or I suspect it will go to someone younger than me,” he said.

But this week, 300 people filled the Moose Lodge hall to hear him speak. Many of them had one of his books tucked under their arms, or copies of the 1994 “Contract With America,” in hopes that Gingrich would have time to sign them.

The candidate was approachable and at ease. He received a standing ovation. Then he climbed into his rented black Chevy Tahoe bound for Philadelphia for the screening of one of his films.