Under-fire US senator Al Franken has said he does not remember whether he touched women inappropriately while having his picture taken with them at campaign events.
The Minnesota Democrat's comments are the latest indication that he has no plans to step down amid allegations of sexual misconduct.
One woman claims he forcibly kissed her on a visit to entertain US troops in Afghanistan and took a sexually suggestive photo while she was sleeping.
Three others allege he grabbed their buttocks while posing with them for photos during separate campaign events in 2007, 2008 and 2010.
"I take thousands and thousands of pictures, sometimes in chaotic and crowded situations," Mr Franken said in an interview aired by CBS. "I can't say I haven't done that. I'm very sorry if these women experienced that."
He added that he has to be "a lot more sensitive, and a lot more careful" when he poses for pictures and when he meets someone: "I'm going to make sure that this does not happen again."
His interviews with Minnesota media outlets over the weekend were his first since he was swept into a nationwide tide of sexual misconduct allegations.
Alabama Republican Senate candidate Roy Moore is accused of initiating sexual conduct with teenagers during the 1970s, and Michigan Representative John Conyers is giving up his leadership position as top Democrat on the House Judiciary Committee amid a congressional probe into claims of sexual harassment. Both men deny the allegations.
Mr Franken told the Minneapolis Star Tribune he does not remember the specific photos, but said such groping is "not something I would intentionally do".
Asked whether he expected other women to step forward with similar allegations, he said: "If you had asked me two weeks ago, 'Would any woman say I had treated her with disrespect?', I would have said no. So this has just caught me by surprise. ... I certainly hope not."
The first woman to come forward was Los Angeles radio host Leeann Tweeden. She released a photo earlier this month showing the then-comedian grinning while reaching out towards her chest, as if to grope her, as she slept on a military aircraft in 2006.
Mr Franken told Minnesota Public Radio on Sunday the photo was "inexcusable".
"What my intention was doesn't matter. What matters is that I am chained to that photo," he said.
"She ... didn't have any ability to consent. She had every right to feel violated by that photo. I have apologised to her, and I was very grateful that she accepted my apology."
Ms Tweeden said he also forcibly kissed her while rehearsing for a show, but Franken has said he has a different recollection of the rehearsal.
He faces a Senate ethics investigation - which he welcomed in the wake of Ms Tweeden's allegation - athough it is unclear when that may begin.
Mr Franken, who has not faced widespread calls to resign, said he will fully co-operate.
He missed Senate votes after the first accusations were made public. He said he spent the holiday break with his wife and the rest of his family, and when he goes back to work he will ask tough questions about proposed tax legislation that "would affect Minnesota and the rest of the country in a terrible way".