It might have been back in February when he got under the skin of New Jersey Gov. Chris Christie on CBS' "Face the Nation."

Or maybe it was in May when he went toe to toe with former House Speaker Newt Gingrich on NBC's "Meet the Press."

None of the analysts is sure exactly when it happened. But they all agree that sometime in 2012, Maryland Gov. Martin O'Malley become a staple, if not a star, of Sunday morning public-affairs television. And for all the new media speaking to voters, that forum not only shapes the national debate, it also plays a major role in anointing politicians as national leaders worthy of White House consideration.

Why does O'Malley get invited to the shows seemingly every week while many other eager and able political leaders never get the call? People who host and book the shows say political savvy, TV skills, geography and a willingness to take off the gloves result in a combination that one veteran network producer describes as "the Chris Christie of Democrats."

"He really has jumped out and established himself on Sunday shows this year as one of the leading spokesmen for the Obama campaign and for Democrats in general," says Bob Schieffer, host of CBS News' "Face the Nation," on which O'Malley has appeared three times in 2012.

"Coming up with people who can speak in an informed and authoritative way isn't easy, and O'Malley is one of the few who can," he adds. "He can tell us what the Obama campaign is up to with straight answers to our questions. And beyond that, he's just very, very good on television — he's a performer who knows how to get his points across. All the shows have figured out how good he is now."

But a higher profile can also make for a better target. Some critics say O'Malley spends more time using the national media to look like he's governing than actually doing the work of running the state in tough economic times. They see him as a camera-loving politician looking to the White House in 2016. But even his harshest critics acknowledge what producers and hosts see: that he is a very effective TV communicator.

"There are a lot of things that make him a good guest," says Candy Crowley, host of CNN's "State of the Union" where O'Malley also appeared three times this year.

"First of all, he runs the Democratic Governors Association, so it gives him heft. Second of all, he is regularly in touch with the Obama people, so that gives him credence," she says.

"But also important ... he's a showman. He gets what his role is. He gets what my role is. And he's game. So far as I can tell, he tells the truth and is very good at nuancing things, so that he doesn't reflect badly on the president even when he disagrees with him. He knows how to walk that line. He gives you enough so that you've got something. But he doesn't give so much that he's then seen by the Obama people as, 'OK, we don't want this guy on again.'"

Crowley adds one other item to the list of what makes the 49-year-old ex-mayor of Baltimore a favorite of the people who make Sunday morning TV: proximity. The Annapolis resident lives within 45 minutes of the Washington studios where the shows are produced. That's no small matter; such logistics count when doing a live, off-the-news telecast.

"It's not that we don't do remote guests," Crowley says. "We do them all the time. But it's so much better when they're in studio, and he can do that. And he's willing to do it. I love that."

Some analysts have attributed O'Malley's rise in national stature solely to his taking over as chair of the Democratic Governors Association in 2011. Yet predecessors Jack Markell of Delaware, Joe Manchin of West Virginia and Bruce Schweitzer of Montana did not see the same profile boost.

Like Crowley, "Meet the Press" executive producer Betsy Fischer Martin says O'Malley's role with the governors' association helped get him onto the shows, but the kind of media game he brought to their studios is what got him invited back. He's been on the NBC show twice this year.

"He's very accessible and willing to come on and engage with Republicans," she says. "The last time we had him on, he was on with Newt Gingrich, and we had a good back-and-forth on the campaign and the major issues going forward. Sometimes we get a situation where we have guests who don't want to appear with the other side. But he's willing to do that. He can be the sort of Chris Christie of Democrats, if you will."

Christie himself offered a less-flattering assessment of Maryland's governor after their February appearance on "Face the Nation."

"Governor O'Malley is not really worthy of responding to," Christie told a reporter from after the show. "I'll tell you the truth: He's not that smart. He's not that good. But he's flippant, so I give him credit for that."

O'Malley had compared Christie to comedian Don Rickles on-air, and not in a good way: "Chris Christie's brand of sort of 'Don Rickles' leadership is unusual. The bombast and all of that stuff is entertaining, but it doesn't make for good governance."

What Christie characterizes as flippant, others might call TV-glib, in a good way.

On July 8, he squared off with Bobby Jindal on ABC's "This Week." The Louisiana governor said America was "going the way of Europe" thanks to what he characterized as the president's failed economic policies.