Mark Sanford: ‘I’ve been unfaithful to my wife.’

After apologizing to nearly everyone — his sons, his wife, his staff, his supporters, residents of South Carolina — Gov. Mark Sanford just said this:

“I’ve been unfaithful to my wife. I developed a relationship which started with a dear, dear friend from Argentina.”

Gov. Mark Sanford arrives at Hartsfield-Jackson International Airport this morning, from Argentina. Gina Smith/The State

A reporter asked if he was alone when he was in Buenos Aires. “Obviously not,” he said. The other woman wasn’t named, but the governor said the relationship “sparked” while he was offering advice on her failing marriage.

The affair was discovered — presumably by his wife — five months ago, but had lasted about a year. “I spent the last five days of my life crying in Argentina,” he said.

The press conference was the finish of a six-day saga in which Sanford dropped off the state’s radar, with his staff stumbling to make excuses for his absence. On Monday, his spokesman told reporters that he was incommunicado, hiking the Appalachian Trail.

Weirdly, the press conference began with a reverie by Sanford of his days — as a high schooler and college student — as an outdoorsman planning trips on the trail. He admitted he gave his staff a mistaken impression of his whereabouts, and the press conference took a more somber turn:

“I’m a bottom-line kind of guy. I’ll lay it out, it’s going to hurt, and we’ll let the chips fall as they may,” he said.

Gov. Mark Sanford wipes away tears during Wednesday news conference. Associated Press.

Sanford said he’s resigning as chairman of the Republican Governors Association, a platform that could have served him well in a 2012 presidential campaign. Haley Barbour, governor of Mississippi, will replace him.

“While this news is deeply disappointing, I also know it’s important to remain focused on the future and Governor Sanford’s resignation allows him and us to do just that,” Barbour said in a prepared statement.

Nick Ayers, executive director of the RGA and a protege of Gov. Sonny Perdue, added this: “My job allows me to share the joys of getting to know great leaders around the country and experiencing great pride when they succeed, but the other side of that is experiencing deep disappointment when they fall short. Today is undeniably a disappointing day.”

Sanford’s admission to adultery comes just a week after U.S. Sen. John Ensign of Nevada, a social conservative spoken of as presidential material, admitted to a months-long affair with an aide and resigned as chairman of the Republican Policy Committee, a top Senate leadership position.

Sanford asked the media for a zone of privacy — if not for himself, then for his sons and wife. But he was walking away from reporters and did not answer when asked if he would resign as South Carolina’s governor.

The press conference was broadcast live on TV in South Carolina, and over the Internet by C-SPAN.

Here’s a partial account of the news conference from The State, which snagged an interview with Sanford this morning as he walked off a plane that had just docked at Hartsfield-Jackson:

“It began very innocently as I expect many of these things do, just casual email back and forth,” Sanford said. “But here recently this last year developed into something much more.”

Asked if Sanford was separated from his wife, he said “I don’t know how you want to define that. I”m here and she’s there. I guess in a formal sense we are not.”

Sanford said his wife has known about the affair and they have been working through it for the past five months. “What I did was wrong, period. End of story,” he said.

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