New York senator Kirsten Gillibrand has accused Donald Trump of a "sexist smear" after the US president attacked her personally following her call for him to resign over sexual misconduct allegations.
Ms Gillibrand is one of at least 100 Democratic members of Congress who have called for an investigation into the claims against the president, after three women who had previously accused Mr Trump of sexual harassment restated their allegations this week.
The wave of sexual harassment scandals that has swept through the US have threatened to ensnare the White House, reviving allegations about Mr Trump's sexual behaviour that surfaced during last year's election campaign.
In a series of early-morning tweets on Tuesday, Mr Trump accused the women of "fabricating stories", and blamed the Democratic Party for peddling "false accusations" and "fake news" about his behaviour.
"Despite thousands of hours wasted and many millions of dollars spent, the Democrats have been unable to show any collusion with Russia – so now they are moving on to the false accusations and fabricated stories of women who I don't know and/or have never met. FAKE NEWS!", he said on Twitter.
But the controversy took a personal turn when the president singled out Ms Gillibrand, claiming that she had come to his office “begging” for campaign contributions “and would do anything for them”.
The barb, which was perceived by many as sexually-loaded, sparked a backlash among female politicians in particular, with Ms Gillibrand saying she would not be silenced.
“It was a sexist smear attempting to silence my voice, and I will not be silenced on this issue,” she said. “Neither will the women who stood up to the president yesterday.”
Ms Gillibrand has emerged as a strong voice in support of victims of sexual harassment in recent weeks. A close ally of the Clintons, she controversially said last month that she believed Bill Clinton should have resigned during the Monica Lewinsky scandal 20 years ago.
Senator Elizabeth Warren, whom the president has previously disparagingly referred to as "Pocahontas", also accused Mr Trump of trying to "bully, intimidate and slut-shame" her Democratic colleague.
Jackie Speier, a Democratic member of the House of Representatives, described Mr Trump's comments as "grotesque", claiming his conduct represented the conduct of a person who was "ill-equipped to be the president of the United States".
But White House press secretary Sarah Sanders rejected the allegations of sexual innuendo on Mr Trump's part, stating "only if your mind is in the gutter would you have read it that way".
“He’s talking about the way our system functions. That politicians repeatedly beg for money. This comment is not new. He has used that same terminology many times in reference to men. There is no way that this is sexist at all,” she said.
The controversy emerged as Alabaman voters went to the polls to elect a successor to former senator Jeff Sessions in an election that has been dominated by allegations of sexual misconduct against the Republican candidate Roy Moore. Donald Trump has endorsed the firebrand candidate, urging voters in an election-day tweet to "do the right thing" and vote for Mr Moore.