US President Donald Trump has claimed that Senator Kirsten Gillibrand was once "begging" him for campaign contributions and that she "would do anything for them" in a tweet on Tuesday.
He wrote: "Lightweight Senator Kirsten Gillibrand, a total flunky for Chuck Schumer and someone who would come to my office 'begging' for campaign contributions not so long ago (and would do anything for them), is now in the ring fighting against Trump. Very disloyal to Bill & Crooked-USED!"
A number of Mr Trump's critics immediately found his tweet itself a form of harassment and took it as suggestive innuendo about a female.
Mika Brzezinski said on "Morning Joe" that it was "derogatory and disgusting."
Senator Elizabeth Warren wrote on Twitter: "Are you really trying to bully, intimidate and slut-shame @SenGillibrand? Do you know who you're picking a fight with? Good luck with that, @realDonaldTrump. Nevertheless, #shepersisted."
Ms Gillibrand responded by writing on Twitter, "You cannot silence me or the millions of women who have gotten off the sidelines to speak out about the unfitness and shame you have brought to the Oval Office."
Following her tweet, Ms Gillibrand held a press conference where she was asked by a reporter if she was offended by the alleged "insinuations" in the US president's tweet.
"It was a sexist smear attempting to silence my voice," she responded.
"I will not be silenced on this issue and neither will the women who stood up to the president yesterday and neither will the millions who have been marching since the women's march to stand up against policies they do not agree with."
"I see it as a sexist smear, that's what it is. It is part of the president's effort of name calling and it is not going to silence me - it is intended to silence me - it's not going to silence the women that have stood up against him directly and it's not going to silence the millions of women out there who are speaking out every day since his inauguration about things they disagree with."
Senator Kirsten Gillibrand, D-N.Y., attends a news conference, Tuesday, Dec. 12, 2017, on Capitol Hill in Washington. Source: AP
Ms Gillibrand, often mentioned as a 2020 presidential prospect, has been one of the leading voices on Capitol Hill in speaking out against sexual harassment and sexual misconduct.
Last week, she was the first of Democrats in Congress to call for the resignation of Senator Al Franken who was facing claims of unwanted sexual advances and groping.
A cascade of senators followed Ms Gillibrand in calling for Franken to step down. A day later, he announced that he would leave the Senate within weeks.
On Monday, three women who accused Mr Trump of inappropriate behavior and sexual harassment reiterated claims they made during the campaign. It was part of a promotional tour for a new video short, "16 Women and Donald Trump" that highlights 16 women who accuse Trump of sexual impropriety. He denies the claims.
Federal Election Commission records show that Mr Trump gave Ms Gillibrand $1,050 in 2007, when she was a member of the House of Representatives, and $4,800 in 2010, after she was appointed to the Senate.
Three women who claim they were sexually harassed by Trump before he ran for president urged lawmakers Monday to open an inquiry into his behavior and allegations of misconduct.
Rachel Crooks, who worked as a receptionist in Trump Tower in New York, says the Republican president forcibly kissed her on the mouth after she introduced herself to him in 2005.
Jessica Leeds, who says she was groped and forcibly kissed by Trump on a commercial flight decades ago, said the president has not been held accountable for "what he is and who he is."
On Twitter, Trump struck back - and seemingly accused Democrats of egging on the women who addressed reporters about the alleged harassment.
"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 tweeted.
A group of 54 Democratic women in Congress called for a probe on Monday, and Democratic Senator Kirsten Gillibrand called on Trump to resign.
