President Donald Trump has criticised Senator Al Franken on Twitter after the Democrat apologised for a photo of him appearing to grope a woman.
Mr Trump called him "Al Frankenstien" - a misspelled reference to the undead monster - and mocked his previous advocacy for women's' rights.
Mr Franken apologised to his accuser, but disputed "forcibly" kissing her.
Mr Trump has yet to publicly comment on sexual misconduct allegations against Republican Senate candidate Roy Moore.
"The Al Frankenstien picture is really bad, speaks a thousand words," Mr Trump wrote in a pair of tweets late on Thursday.
Los Angeles radio host Leeann Tweeden claims the now-Minnesota senator "aggressively" kissed her while they rehearsed a scene during a 2006 tour to entertain US troops in the Middle East and Afghanistan.
He also had a photo taken of him appearing to touch her breasts while she slept onboard a military plane, she said.
The Al Frankenstien picture is really bad, speaks a thousand words. Where do his hands go in pictures 2, 3, 4, 5 & 6 while she sleeps? .....— Donald J. Trump (@realDonaldTrump) November 17, 2017
.And to think that just last week he was lecturing anyone who would listen about sexual harassment and respect for women. Lesley Stahl tape?— Donald J. Trump (@realDonaldTrump) November 17, 2017
"And to think that just last week he was lecturing anyone who would listen about sexual harassment and respect for women", Mr Trump said in a follow-up tweet.
Mr Trump has yet to comment on a string of sexual misconduct allegations against Republican US Senate candidate Roy Moore.
The former Alabama Supreme Court judge denies has repeatedly denied the allegations and has resisted calls from his own national party to quit the US Senate race.
Hours before the tweets, White House President Secretary Sarah Sanders said the president found the allegations against Mr Moore "very troubling" and that "the people of Alabama should make the decision on who their next senator should be".
Mr Trump has himself denied numerous allegations of sexual misconduct against him. During the second presidential debate, he was asked if he had ever grabbed anyone's genitals or kissed them without consent.
"Women have respect for me. And I will tell you: No, I have not," he replied.
Later, when asked to explain the distinction between the allegations against Mr Trump and Mr Franken, Mrs Sanders said: "Senator Franken has admitted wrongdoing, and the president hasn't. That's a very big distinction."
In an article for KABC, a Los Angeles radio station where Ms Tweeden now works, she recalled feeling victimised by Mr Franken during her ninth tour of the Middle East.
"You knew exactly what you were doing," she wrote. "You forcibly kissed me without my consent, grabbed my breasts while I was sleeping and had someone take a photo of you doing it, knowing I would see it later, and be ashamed."
The former comedian issued an initial statement saying he did not recall the rehearsal, but sent his "sincerest apologies to Leeann".
"As to the photo, it was clearly intended to be funny but wasn't. I shouldn't have done it," he added.
Mr Franken later issued a second, longer statement following a backlash from critics who accused him of a non-apology and demanded his resignation.
"I respect women. I don't respect men who don't. The fact that my own actions have given people a good reason to doubt that makes me feel ashamed," he said.
I want to apologize to Leeann Tweeden, to everyone who was part of the USO tour, to all who've worked for me, to all I represent, & to all who've considered me an ally & supporter & champion of women. I am sorry. https://t.co/vrLCIcggg6— Sen. Al Franken (@SenFranken) November 16, 2017
Of the photo, he added: "I look at it now and I feel disgusted with myself... It's obvious how Leeann would feel violated by that picture."
In Mr Trump's tweets on Thursday night, he also mentioned the "Lesley Stahl tape", which refers to a New York magazine story about a Saturday Night Live writers discussion in which Mr Franken suggested a joke about raping the CBS 60 Minutes correspondent.
Mr Franken was quoted as saying: "And, 'I give the pills to Lesley Stahl. Then, when Lesley's passed out, I take her to the closet and rape her.' Or, 'That's why you never see Lesley until February.' Or, 'When she passes out, I put her in various positions and take pictures of her.'"
Senate Democratic leader Chuck Schumer called for the chamber's Ethics Committee to investigate Mr Franken, saying: "Sexual harassment is never acceptable."
The Republican Senate leader Mitch McConnell echoed the call and Mr Franken said he would "gladly co-operate".