Senator Al Franken announced he is resigning from the US Senate following series of sexual misconduct allegations.
Mr Franken, 66, who represents Minnesota in the 100-seat US Senate, had come under increasing pressure from his own Democrat colleagues to step down.
The former comedian was encouraged to resign as Democrats sought to maintain the moral high ground in the wake of sexual misconduct allegations against Roy Moore, the Republican senate candidate in Alabama.
Mr Franken said: "I, of all people, am aware there is some irony that I am leaving while a man who has bragged on tape about his history of sexual assault now sits in the Oval Office."
Mr Franken, who made his name on the popular late-night comedy show Saturday Night Live before turning to politics, has acknowledged misconduct with at least one accuser.
Six other women have reportedly come forward to accuse him of touching them inappropriately.
Speaking on the Senate floor Mr Franken said he had been a "champion of women" during his time in office.
He said: "Some of the allegations against me are simply not true, others I remember very differently.
"I know there has been a very different picture painted of me in recent weeks but I know who I am."
Referring to Roy Moore, the Republican Senate candidate in Alabama, he added: "And a man who has preyed on young girls campaigns for the Senate with the full support of his party."
Mr Franken did not admit any guilt, and did not apologise to any of the alleged victims during his resignation speech.
Mr Franken claimed that, had he stayed and been investigated by the Senate ethics committee, he would have been cleared.
But a majority of his Democrat colleagues in the Senate had called for him to resign.
Mr Franken was first accused last month by Leeann Tweeden, a sports broadcaster and former model, who said he forcibly kissed her, and touched her without consent as she slept, during a 2006 tour entertaining US troops deployed in Afghanistan.
Following Mr Franken's resignation Minnesota's Democratic governor, Mark Dayton, has the power to appoint a replacement.
The Star Tribune newspaper said the likeliest replacement is the lieutenant governor, Tina Smith, who would serve until a November 2018 special election.
It came just days after Democrat John Conyers, the longest-serving member of Congress, left the House of Representatives after several female former staffers accused him of sexual misconduct.