Martin O'Malley lets out a scream as he jumps out of the frigid Chesapeake Bay in the 2011 Polar Bear Plunge. (Jonathan Newton/The Washington Post)

Martin O’Malley is not the best-known Democrat running for president (Hello, Hillary!). Nor is he the fire-breathing socialist talking of tearing up Wall Street (Bernie Sanders, come on down!).

Yet, depending on one’s taste, O’Malley may command at least one category: the swimsuit competition.

O’Malley in all his shirtless glory is alive and well-toned in photos snapped when he was Maryland’s governor, and those images are circulating with renewed vigor as he seeks the White House.

There he was wading into the ocean at a 2012 charity event, then a beaming 49-year-old with taut abs and sculpted biceps. There he was in a swimming pool juggling beach balls, his buff physique the envy of any middle-aged stooge.

Sen. Barack Obama surfs at Sandy Beach in Honolulu, Hawaii in 2008. (Alex Brandon/AP)

O’Malley’s campaign is not touting photos of his un-dad-like bod, preferring images of him plucking a guitar or appearing to contemplate grander horizons. But the former governor’s pectorals, perhaps unwittingly, are another way to remind voters that he’s considerably younger than a certain 67-year-old former first-lady-turned-senator-turned-secretary-of-state.

“It’s certainly helpful in a campaign where youth and new ideas are going to be part of the discussion,” said Hank Sheinkopf, a Democratic consultant who has worked for the Clintons. “Physical fitness implies younger and new ideas — in other words, non-Washington. Because when you’re in Washington, all you’re doing is sitting in meetings and not getting fit.”

Of course, a shirtless pol can also suggest a decidedly unpresidential pol. Americans, whatever their electoral whims, have never demonstrated a predilection for choosing bimbos (or himbos).

“The downside,” Sheinkopf said, “is some people will say that he’s not serious.”

No one would draw that conclusion about the ever-brooding Vladi­mir Putin, the Russian president who has been photographed fishing, horseback riding and holding a rifle — all without a shirt. Barack Obama, on the other hand, seethed when photographers scored topless shots of him vacationing in Hawaii in 2008.

In the swarm of Republicans and Democrats vying to succeed President Obama, the candidates’ unceasing challenge is to distinguish themselves. Sen. Ted Cruz’s moment may have been reading “Green Eggs and Ham” in the Senate chambers. Jeb Bush has the two Georges. Hillary Rodham Clinton has Bill, not to mention Whitewater, Monica and more.

Russian Prime Minister Vladimir Putin rides a horse during his 2009 vacation in Southern Siberia. (Alexsey Druginyn/AFP/Getty Images)

O’Malley, Baltimore’s mayor before his gubernatorial term began in 2007, can tout a litany of greatest hits that include enacting immigration reform, promoting wind power and championing a government accountability system known as CitiStat.

His record may titillate progressives, but few are betting it’s enough to steal the Democratic show, let alone surpass 10 percent in the polls.

“Shirtless, pantsless — he’s got to do anything he can to stand out,” said Fred Davis, a Republican consultant who knows all about politicians who are happy to strip down.

Davis advised Sen. Jeff Flake (R-Ariz.), whose 2009 bare-chested selfie (when Flake was a House member) inspired the headline, “D.C.’s New Beefcake” (not to be confused with then-Rep. Aaron Schock’s six-pack-displaying spread two years later, titled “The Ripped Representative”).

In Flake’s case, “it was authentically Jeff,” Davis said. In O’Malley’s case, Davis sees more substantive ways to question the Democrat’s candidacy than his willingness to bare himself before photographers.

“Do you really want the former mayor of Baltimore as president?” Davis asked.

If not for his White House quest, O’Malley’s portfolio of topless grandeur probably would remain known only to his most ardent admirers. But as O’Malley prepared to announce his candidacy, the Drudge Report gave the photos new life, repeatedly displaying them for millions of viewers when linking to articles about the former governor.

“Someone should start counting how many times Drudge puts a picture of O’Malley on his site without a shirt on,” Jeff Greenfield, the political commentator, tweeted last week.

Haley Morris, an O’Malley spokeswoman, suggested that the campaign is oblivious to the fuss. “It appears you’ve given these photos much more thought than we have,” she said before using the opportunity to add a plug for her boss’s “progressive values and record.”

Back in the day, Americans probably would have blanched at the sight of President John Adams and his hairless pate romping in the waves. History records no evidence of anyone clamoring for Abraham Lincoln to climb into the 1860s version of a Speedo. And William Howard Taft, weighing in at 350 pounds, was hardly the stuff of cheesecake shots.

“It was working-class men who were fit then and it was the upper class that was plump,” said Michael Kazin, a Georgetown University political science professor. “There were all those images of plutocrats with big stomachs. And now it’s people who are powerful who exercise.”

Teddy Roosevelt may have been the first president to trumpet himself as more than a guy behind a big desk, riding horses in Rock Creek Park and boxing in the White House. But the phrase “presidential sex appeal” likely did not exist until John F. Kennedy ambled into politics with his smiling, square-shouldered gait, often celebrated in Life magazine.

At times, politicians have shown their fitness in order to prove something. In 1992, Paul Tsongas, a senator from Massachusetts who was running for president, swam the butterfly stroke to convince voters he had licked cancer. But Bill Clinton won the presidency that year, after Americans somehow made sense of his simultaneous passions for Big Macs and jogging (not to mention those short running shorts).

For all the attention candidates devote to appearance, physical attractiveness does not guarantee political success. Just ask John Edwards and Mitt Romney, both of whom likely could have found work as J. Crew catalogue models after their presidential campaigns tanked.

“How many Republicans are going to say, ‘We’re voting for Barack Obama because he’s good looking,’ ” said Ryan Enos, a Harvard professor who studies political psychology. “As best we can tell, it doesn’t matter.”

O’Malley’s supporters insist their guy is a wonkish nerd, more interested in policy than preening. Yet O’Malley has demonstrated that tending to his own pecs is more than a fleeting interest.

He acknowledged in February that he works out at a gym when he reported that he had broken his elbow while pumping iron.

“Surgery went well,” O’Malley tweeted. “I’m on the road to a quick recovery.”

The former governor’s tweet did not include a photograph.