Mere minutes after receiving an endorsement from Texas Gov. Rick Perry, Republican presidential candidate Newt Gingrich told a crowd of supporters Thursday in Beaufort that he is the only remaining conservative capable of beating former Massachusetts Gov. Mitt Romney for the party's presidential nomination.

Flanked by his wife, Callista, Gingrich held an hour-long town-hall meeting before a crowd of more than 500 people that spilled out of the pavilion at Henry C. Chambers Waterfront Park.

The event, one of two Gingrich held Thursday in Beaufort County, was delayed for about 20 minutes while Gingrich sat on an idling campaign bus, where he watched Perry bow out of the race and give the former speaker his endorsement.

Upon taking the stage, Gingrich said he was "very honored and very humbled" by Perry's support before taking President Barack Obama to task on national security, foreign policy and the administration's decision to reject a Canadian firm's plans to build and operate the Keystone XL pipeline, a massive project that would have connected oil sands in Canada to refineries in Texas.

Gingrich characterized Obama as a president in over his head.

"I've told people, it's one thing if a White House can't play chess," he said at an event earlier Thursday in Sun City Hilton Head. "It's another thing if they can't play checkers. But if they can't even play tic-tac-toe..."

He also sharply criticized the president's plans to hold a town hall meeting at the Magic Kingdom at the Walt Disney World resort near Orlando, Fla., claiming the president's visit would inconvenience vacationing families.

"As I thought this morning about the president flanked on one side by Mickey Mouse and on the other side by Goofy, kind of resembling a cabinet picture of the Obama administration, I just felt better about the idea," Gingrich said to raucous applause.

Gingrich then opened the Beaufort forum for questions. He was asked about upcoming debates and the economy before retired Marine Staff Sgt. Will McCullough of Beaufort briefly stole the show by asking Gingrich to explain his "personal lapses in judgment," including recent accusations that he asked his second wife for "an open marriage" in 1999.

Gingrich acknowledged past "mistakes" but did not respond directly to the new allegations.

"I've been very open about my life and very open about the mistakes I've made," Gingrich said. "Callista and I have a wonderful relationship. We knew that when we decided to do this that we would get beaten up, that we would get lied about and that we would be smeared ... but we decided that this country was worth the pain."

Though an uncomfortable question, McCullough said it was one he felt compelled to ask before voting in the state's primary Saturday.

"I'm personally torn between (Texas Sen.) Ron Paul and Speaker Gingrich, and I promised myself that if I ever got to ask him that question, I would," McCullough said. "I got the opportunity today. I thought it was a good answer. I thought he was genuine. Unlike some of the other candidates, we all know (Gingrich's) issues, and you can take it or leave it. That's something you have to decide for yourself."

--Staff writer Kyle Peterson contributed to this report.

Follow reporter Patrick Donohue at twitter.com/ProtectServeBft.