Did John King blow it?

The CNN host stepped on a land mine named Newt Gingrich when he opened Thursday night’s Republican presidential debate by asking him about his second ex-wife’s allegation that he suggested she accept his affair as part of their marriage.

Gingrich’s now-famous response practically blew back King’s hair. “I think the destructive, vicious, negative nature of much of the news media makes it harder to govern this country, harder to attract decent people to run for public office,” he said to thunderous applause during the forum in Charleston, S.C. “And I am appalled that you would begin a presidential debate on a topic like that.”

To even more enthusiastic applause, the former House speaker added, “I am tired of the elite media protecting Barack Obama by attacking Republicans.”

Gingrich’s shoot-the-messenger answer may be one of the most memorable moments of the campaign and a potential boost for his candidacy against front-runner Mitt Romney.

Question is: Did King — an experienced and able journalist — do Gingrich a favor by starting the debate with such an indelicately posed question on such a delicate issue? And was he prepared with a follow up once Gingrich got rolling?

In the face of Gingrich’s initial blast, King could only offer that the allegations about Gingrich “did not come from our network.” (The Washington Post and ABC News were the initial sources of the report.) That allowed Gingrich to up the ante and scold King further: ”Don’t try to blame somebody else.”

In post-debate comments, King seemed to have few regrets. “I understood that if I asked the question, he was not going to be happy with it, and he was going to turn on me. Knew that coming in,” he said during an interview with CNN’s Anderson Cooper immediately afterward. (King was unavailable for an interview Friday.) “This is one of those damned if you do, damned if you don’t. It was my judgment, my d e cisi on and mine alone. If we’re going to deal with it, let’s deal with it upfront, let’s not try to sneak it into the middle of the debate somewhere.”

King didn’t back down Friday night in a segment of “John King, USA,” the daily CNN show he began hosting in 2009, a dozen years after arriving at the network and quickly rising to senior White House correspondent.

“I was doing my job as I see it, and [Gingrich] was doing his,” said King, 48. “I take no offense in him turning on me.” He also ran a series of clips of Gingrich attacking the media, adding, “Let’s not ignore the obvious and time-tested calculation in the Speaker’s response.”

But maybe it wasn’t that simple. Some observers found flaws in King’s approach.

“Gingrich was clearly waiting for the question, clearly was prepared to pounce,” said W. Joseph Campbell, a communications professor and media historian at American University. “King seemed taken off guard. He looked a little sickened. And he did himself no favors by lamely pointing out that it wasn’t CNN but another network that dug out the Gingrich-infidelity story. That allowed Gingrich to pounce again.”

King would have been on safer ground if one of the other candidates had brought up the issue, which was the talk of the campaign all day Thursday, said Terence Smith, a veteran journalist who was the longtime media correspondent for PBS’s “NewsHour.”

“That would have made it far easier for him to bring it up,” Smith said. “There’s no guarantee that anyone would have mentioned it, but it was likely,” given how prominent the story had been all day.

As it was, King’s handling of the issue seemed “maladroit,” said Richard Wald, a former president of NBC who is now a professor at Columbia University’s Graduate School of Journalism. “It was not the most sensible way to go about it.”

Wald contrasted King’s handling of the infidelity issue with the way he approached former governor Mitt Romney’s reluctance to release his tax records. King set up his question by noting that Romney’s father, George, had established the precedent of disclosing his taxes by releasing 12 years of records when he was a candidate in the 1960s. The mention of Romney’s father’s behavior may have closed off the possibility of an attack on the media for bringing up the issue, he said.

By the same token, King could have framed the infidelity question better, perhaps by noting that Gingrich’s own attacks on President Bill Clinton’s claim to moral authority and fitness for office in the 1990s amid revelations of his relationship with Monica Lewinsky, Wald said. “The issue certainly is relevant” to socially conservative voters in South Carolina, Wald said, “but this wasn’t set up right. It was like a kid blurting something out.”

King may have missed another chance to follow up on Gingrich’s opening comments during the debate, Campbell said.

Gingrich “was way over the top in claiming that negative media reporting ‘makes it harder to govern this country,’ ” he said. “The American political scene has long been a rough-and-tumble place. . . . You deal with it. It’s not as if negative press is anything new.”

During the opening minutes of his program Friday, King made note of the day’s big development, which may have been a result of the night before: “Polls show Newt Gingrich surging in South Carolina.”