San Francisco Mayor Gavin Newsom said he doesn't know if he's an alcoholic but admitted that drinking had "gotten in the way of my job performance" in his first sit-down interview since acknowledging an affair with a top aide's wife and announcing that he would seek treatment for alcohol use.

Newsom told KPIX-TV on Wednesday that he's been attending counseling sessions at Delancey Street Foundation for several hours each night, and the treatment is helping him examine why he felt the need to "drink to an extreme."

"I don't need to drink now. I need more time to reflect," he said. "I've got to be ready, focused, and clear."

Newsom, who's currently seeking a second term, shot down allegations that he's used cocaine or other illicit drugs, calling the rumors "gratuitously erroneous."

Newsom, 39, said he would seek outpatient treatment at Delancey Street, a residential program for hard-core addicts in San Francisco, just days after the resignation of his campaign manager, Alex Tourk, who had confronted him about his affair with Tourk's wife, Ruby Rippey-Tourk, the mayor's former appointments secretary.

Newsom, who has said little publicly about the affair, told KPIX-TV that the tryst 1 1/2 years ago was "something I'll for the rest of my life regret."

"I'm trying to reconcile things, make amends," he said, "but it's something that's been challenging."