New York Attorney General Eric Schneiderman has resigned following allegations he physically assaulted four women.
Mr Schneiderman, 63, stepped down shortly after The New Yorker magazine quoted the women as saying they had been subjected to non-consensual physical violence during romantic relationships or encounters with him.
A spokesman for the Manhattan District Attorney's office said they had opened an investigation into the allegations.
Mr Schneiderman, a Democrat, had recently emerged as a champion of women's rights and outspoken critic of President Donald Trump.
He had become a vociferous figure in the #MeToo movement against sexual harassment and demanded greater compensation for the victims of Harvey Weinstein's alleged sexual crimes.
Mr Schneiderman said in a statement that he "strongly contests" the allegations.
Statement from Eric T. Schneiderman:
"In the privacy of intimate relationships, I have engaged in role-playing and other consensual sexual activity. I have not assaulted anyone. I have never engaged in non-consensual sex, which is a line I would not cross."
— Eric T. Schneiderman (@Schneiderman) May 7, 2018
But, he added, "while these allegations are unrelated to my professional conduct or the operations of the office, they will effectively prevent me from leading the office's work at this critical time. I therefore resign my office, effective at the close of business on May 8, 2018."
In the statement, he denied abusing the women, saying: "In the privacy of intimate relationships, I have engaged in role-playing and other consensual sexual activity.
"I have not assaulted anyone. I have never engaged in non-consensual sex, which is a line I would not cross."
Soon after the allegations surfaced, Mr Schneiderman came under pressure from fellow Democrats in New York to resign.
New York Governor Andrew Cuomo called for an investigation and said: "My personal opinion is that, given the damning pattern of facts and corroboration laid out in the article, I do not believe it is possible for Eric Schneiderman to continue to serve as Attorney General, and for the good of the office, he should resign."
The New Yorker cites alleged victims Manning Barish and Tanya Selvaratnam as accusing Mr Schneiderman of hitting and choking them, which they later sought medical attention for.
Ms Selvaratnam also said he threatened to tap her phone among other threats.
Both women said the incidents often occurred after Mr Schneiderman had been drinking.
Ms Barish wrote in a Facebook post: "I could not remain silent and encourage other women to be brave for me.
"I could not leave my sisters who had been harmed hanging-discredited-when I knew the truth."
A further two women, who remain anonymous, have alleged that Mr Schneiderman was physically violent towards them.
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Mr Schneiderman's ex-wife Jennifer Cunningham defended him on Monday, saying in a statement that the allegations "are completely inconsistent with the man I know".
The New York Police Department said in a statement that it had no complaints against Mr Schneiderman but would "investigate them thoroughly" if it receives any.