Embattled Sen. John Ensign, widely seen as a possible 2012 presidential hopeful, Wednesday resigned his Senate leadership job after disclosing he had had an affair with a campaign staffer.

The Nevada Republican, who has a history of strong “family values” statements, said Tuesday the affair was “absolutely the worst thing I;ve ever done in my life.”

Ensign was chairman of the Senate Republican Policy Committee. He had become a visible spokesman for the party views and, at 51, was regarded as an up-and-coming party star.

But Wednesday, he told Senate Republican Leader Mitch McConnell in a phone call he would step down from his leadership post. Ensign was not available for comment.

McConnell said, “He’s accepted responsibility for his actions and apologized to his family and constituents. He offered, and I accepted, his resignation as chairman of the Policy Committee.”

Ensign had not ruled out a 2012 White House bid. He visited Iowa, traditionally the site of the nation's first presidential caucuses, a few weeks ago.