Minnesota Senator Al Franken
Minnesota Senator Al FrankenReuters

Minnesota Senator Al Franken succumbed to the demands of a growing number of ranking Democratic politicians calling for his resignation over allegations of sexual misconduct in what is a stunning downfall for a once-popular politician who had been considered as a possible 2020 presidential candidate.

The senator said in a news conference on Wednesday that "he would resign in the coming weeks" after another woman accused him of sexual assault on Wednesday. Franken denied the allegations, saying on the Senate floor that "some of the allegations" against him "are simply not true".

"It's become clear that I can't both pursue the ethics committee process and at the same time remain an effective senator ... I may be resigning my seat, but I will not be giving up my voice," Franken said on the Senate floor.

"There has been a very different picture of me painted over the last couple of weeks" Franken added.

Over 25 Senators had urged Franken to resign after Wednesday's allegation by a former congressional staffer including top-ranking Senate Democrats Chuck Schumer of New York, Dick Durbin of Illinois and Patty Murray of Washington.

Franken also blasted President Trump and Alabama Senatorial candidate Roy Moore in his speech, both of whom have been accused of sexual harassment themselves.

"I, of all people, am aware that there is some irony in the fact that I am leaving while a man who has bragged on tape about his history of sexual assault sits in the Oval Office and a man who has repeatedly preyed on young girls campaigns for the Senate with the full support of his party," Franken said.

"I am proud that during my time in the Senate that I have used my power to be a champion of women," the Minnesota senator said from the US Senate floor.