Larry Hogan, left, Republican candidate for Maryland governor, and New Jersey Gov. Chris Christie speak with reporters at The Pancake House in Bethesda. (AP Photo/Patrick Semansky)

New Jersey Gov. Chris Christie blew through a Bethesda diner on Tuesday morning, providing a 20-minute burst of energy — ­fueled by hearty handshakes and selfies with patrons — to the gubernatorial campaign of Maryland Republican Larry Hogan.

Christie, chairman of the Republican Governors Association and a potential 2016 presidential candidate, told a crush of reporters that he is “living proof” that members of his party can prevail in traditionally Democratic states — noting that he’s now done so twice.

“Larry Hogan’s got the momentum,” Christie said after the two men, trailed by more than a dozen television cameras, said a rapid-fire series of hellos to diners at The Original Pancake House. “I’m a mercenary in this job. I go to places where he can win.”

Christie’s public appearance followed a fundraiser with Hogan in Potomac that was closed to the media. Hogan aides said proceeds would flow into an account set up by the Maryland Republican Party to promote Hogan’s bid. As of late Tuesday afternoon, they had not said how much was raised.

Christie’s help comes with two weeks remaining in a governor’s race that has proved closer than many expected in heavily Democratic Maryland. A Washington Post poll published two weeks ago showed the Democratic candidate, Lt. Gov. Anthony G. Brown, with a lead of nine percentage points over Hogan.

At the diner, a television reporter peppered Hogan with questions about why he has declined to release a questionnaire his campaign filled out for the National Rifle Association. The NRA endorsed Hogan on Monday, giving him a grade of A-minus and saying Brown merited an F on its issues.

“We’re not really here to talk about what Anthony Brown wants to talk about,” Hogan said, adding, “We’re really focused on the governor’s visit here.”

Christie chimed in, saying he “admires the lieutenant governor for trying to change the subject.”

“I’ll just say if I had the lieutenant governor’s record and I had to run for a third Marty O’Malley term, I’d be trying to talk about anything else in the world but that, too,” Christie said, referring to Gov. Martin O’Malley (D), who has endorsed Brown as his successor.

Brown’s campaign debuted a TV ad Tuesday that highlights Hogan’s refusal to release the questionnaire, which included questions about rolling back parts of sweeping gun-control legislation passed last year by the Maryland General Assembly.

In public appearances, Hogan has said he has no plans to ask the legislature to repeal the law. Hogan has made tax cuts the rallying cry of his candidacy, and he has said he does not consider guns to be a major campaign issue.

Gun-control advocates have pressed Hogan to release the NRA questionnaire. On Tuesday, nearly a dozen members of the Maryland chapter of Moms Demand Action for Gun Sense in America made a second trip to Hogan’s campaign office in Annapolis to draw attention to the issue.

“We asked to have the same information that the gun lobby received,” Jennifer Stapleton, a volunteer for the group, said afterward, adding that the request was unsuccessful.

Christie’s appearance in Bethesda buoyed many Hogan supporters at the diner, including about two dozen volunteers pulled together by the campaign.

“Chris Christie’s a national figure,” said Joe Crock, a librarian who came down from Baltimore County. “You don’t see too many Republicans coming to Maryland to fire up the base.”

Asked about his enthusiasm for Hogan, Crock, 27, said: “He’s better than the alternative. Anthony Brown seems like he’s an extension of the current administration.”

Mila Tobin, 67, a homemaker from Chevy Chase, said she was a little ambivalent about Christie when she arrived Tuesday morning, citing photos of the governor and President Obama taken after Hurricane Sandy hit New Jersey.

Christie seemed “genuine” as they talked at the diner, Tobin said, and she came away a fan. She said she plans to vote enthusiastically for Hogan because “in Maryland, we’re being taxed to death, and “he’s the exact opposite of Anthony Brown.”

Brown’s campaign got a boost of its own on Sunday with a visit by Obama. The president urged a crowd in Prince George’s County to take advantage of early voting, which begins Thursday.

On Tuesday, Hogan was asked about his thoughts on a 2016 White House bid by Christie.

“I think he’d made a terrific president,” Hogan said. “I can’t think of anyone who’s done a better job as governor.”

As Hogan walked Christie to a black SUV, Christie told him that he intends to be back next week for another event.