Lindsay Menz said she took a photograph with the senator at a fair in Minnesota in 2010, and that Franken "pulled me in really close, like awkward close, and as my husband took the picture, he put his hand full-fledged on my rear."
Franken told the channel that he did not remember taking the photo with Menz, and that he felt "badly that Ms Menz came away from our interaction feeling disrespected."
Franken's rise from funnyman to darling of the political left has been thrown into doubt by the allegations and the likely opening of a Senate ethics investigation that could see him fined, stripped of committee posts or even expelled.