Trump stuck firm to his unprecedented defiance of US democratic norms, telling supporters: "I will totally accept the results of this great and historic presidential election -- if I win."
But he went on to say: "I will accept a clear election result, but I will also reserve my right to contest and file a legal challenge in the case of a questionable result."
Trump sailed into a new political tempest after threatening not to recognize the election outcome during his final debate with Hillary Clinton, the Democratic frontrunner.
With the November 8 elections three weeks away, Trump insists that Clinton's campaign team and the media are attempting to rig the vote against him.
Asked point-blank during Wednesday's debate whether he would accept the results no matter what, he responded: "I'll tell you at the time. I'll keep you in suspense, OK?"
Clinton declared herself "appalled" by what she said was an attack on American democracy.
New Trump accuser said he groped her at 1998 tennis event
Another woman came forward Thursday claiming that Donald Trump groped her and made inappropriate sexual remarks, adding to accusations of nine other women that have emerged in recent days.
Karena Virginia, 45, a New York-area yoga instructor, said at a news conference that the celebrity billionaire and Republican presidential nominee had made an unwanted sexual advance at the 1998 US Open tennis tournament.
Virginia, reading from a written statement, said Trump pointed at her to other men and said "'hey, look at this one. We haven't seen this one before. Look at those legs' as if I was an object rather than a person."
Virginia, who was 27 at the time, said that Trump grabbed her by the arm and touched her breast.
Karena Virginia addresses the media during a news conference with her lawyer Gloria Alred in New York, Thursday, Oct. 20, 2016 (AAP) Source: AAP
"'Don't you know who I am, don't you know who I am?' he said," according to Virginia's statement.
"I felt intimidated and I felt powerless," she said, adding that she "felt ashamed" for wearing a short dress and high heels.
"That feeling of shame stayed with me for a while," she said.
Virginia spoke to reporters flanked by high-profile discrimination lawyer Gloria Allred, who said that her client "is not considering a lawsuit at this time."
The Trump campaign slammed the latest accusation of sexual misconduct as a tool meant to help Democratic rival Hillary Clinton win the November 8 election.
"Discredited political operative Gloria Allred, in another coordinated, publicity seeking attack with the Clinton campaign, will stop at nothing to smear Mr. Trump," said Jessica Ditto, the Republican's campaign deputy communications director, in a statement.
"Give me a break. Voters are tired of these circus-like antics and reject these fictional stories and the clear efforts to benefit Hillary Clinton," she said.
On October 7 The Washington Post released a 2005 video recording that caught Trump boasting in lewd terms about how he could get away with groping women without their consent because he was a celebrity.
After this aired, nine women came forward to accuse Trump of unwanted sexual advances, some of which if confirmed amount to sexual assault.
Virginia is the 10th woman to level accusations against the Republican White House contender.
During the third and final presidential debate late Wednesday with Clinton, Trump denied all the accusations, saying they were "fiction" and "have been largely debunked," even suggesting that Clinton had planted them.
"No one has asked me to come forward," said Virginia. "In fact, many people advised me not to speak publicly."
According to an official biography in The Huffington Post, where she sometimes writes, Virginia is "a wellness expert... motivational speaker, energy healer, yogi, inspirational mentor and TV personality," and as a child "was highly sensitive to angels."
