Former Apprentice contestant Summer Zervos has filed a defamation lawsuit against Donald Trump, accusing him of unwanted sexual contact and failing to admit it.
Mr Trump could not be immediately reached for comment. He has previously denied all claims of sexual assault and sexually inappropriate behaviour with women.
Mr Trump was accused of repeatedly kissing and groping Ms Zervos around the time she was taking part in the fifth series of The Apprentice.
Just days before Mr Trump is about to be inaugurated, her lawyer, Goria Allred, led Ms Zervos into the Los Angeles-based press conference by the hand and read out a statement.
She said Mr Trump was asked two months ago to retract his statements about Ms Zervos.
"There is no good time [to file the lawsuit]. There is no bad time. We were patient. But time is up," she said.
"Time to face the consequences," she added. "Women are not a footnote to history."
She alleged that her client had been subjected to unwanted sexual touching by Donald Trump and that she had told family and friends about the incidents not long after the incident occurred.
She did not go public at the time, as she "decided Donald Trump's behaviour had been aberration, a test, or he may have even regretted or been ashamed of his behaviour".
Ms Zervos decided to pursue her case after she saw the leaked 2005 Access Hollywood video in which Mr Trump bragged to host Billy Bush about grabbing women's genitals. She said his words were consistent with what she had experienced with him.
The President-elect then told CNN's Anderson Cooper during a debate that he had never acted inappropriately to women. Those two factors convinced Ms Zervos to go public, Ms Allred said.
Ms Zervos said she would be willing to immediately retract the lawsuit with no monetary compensation or legal fees if Mr Trump would admit his alleged crime. She added she wanted to repair her "reputation".
The lawyer said she would subpoena NBC for out-takes of Mr Trump on The Apprentice to obtain evidence of his alleged behaviour towards Ms Zervos during the making of the show.
The lawsuit was filed in New York on 17 January for a "minimal, jurisdictional" amount of damages, because "what we really want is to prove defamation", said Ms Allred. Her client is also suing for emotional distress, but is not suing Mr Trump for alleged sexual assault.
Ms Allred said her client "could no longer rationalise or excuse" Mr Trump's alleged behaviour.
"Mr Trump had no shame," said Ms Allred.
At least 13 other women have accused Mr Trump of sexual assault, and he has denied all of these claims, accusing the women of lying, being hungry for fame and being "sick".
The lawsuit is the first to be filed since another unidentified accuser dropped her lawsuit which accused Mr Trump of raping her when she was a child. He strongly denied this allegation.
"Truth matters. Women matter. Those that allege they were victims of sexual assault or sexual misconduct by Donald Trump matter," said Ms Allred.
She added that her client had volunteered to take a polygraph test about her statement, and she passed.
Ms Allred said Ms Zervos was "brave" and she knew she would receive "unwarranted attacks" by Mr Trump.
When asked if Ms Zervos' case would be Ms Allred's last case against the President-elect, she replied: "I certainly hope not".
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