LAS VEGAS (AP) -- Republican Sen. John Ensign of Nevada, damaged politically and facing a Senate ethics investigation over an extramarital affair, said Monday he won't seek re-election next year.
Ensign, who is under investigation by the Senate Ethics Committee, said he decided last week against seeking a third term because he was worried about the effect of a campaign on his family.
"I'm putting them first, instead of my career," Ensign said.
Ensign, 52, acknowledged in June 2009 that he had an extramarital affair with Cynthia Hampton, a former member of his campaign staff, and that he had helped her husband, Doug Hampton, a member of his congressional staff, obtain lobbying work with a Nevada company.
In recent months, Ensign had been adamant that he would seek re-election and that he did nothing to violate the law or Senate ethics rules.
Ensign insisted the ethics investigation didn't affect his decision to retire, and he again denied he broke the law or ethics rules.
"It had zero effect," the senator said. "If I was concerned about that, I would resign. That would make the most sense, because then it would go away."
Democratic Senatorial Campaign Committee chief Guy Cecil promised a grassroots effort to elect a Democrat to replace Ensign.
"Whoever Republicans field as their candidate will have a tough time holding onto this seat in a blue-trending state with President Obama at the top of the ticket," Cecil said.