Democratic presidential candidate Joe Biden has denied allegations he sexually assaulted a former staff assistant in the early 1990s.
The 77-year-old said the alleged attack, which is said to have taken place when Mr Biden was a Senator, "never happened".
It is the first time Mr Biden has personally addressed the allegations which have been circulating his campaign for several weeks. The woman filed a criminal complaint to police last month.
In an interview on MSNBC's "Morning Joe" show, Mr Biden said: "I’m saying unequivocally, it never, never happened."
Mr Biden said he would try to clear his name by asking the National Archives to determine whether any record of such a complaint filed was against him. He said he was sure no such record existed.
The former Vice President said: “The former staffer has said she filed a complaint back in 1993.
“But she does not have a record of this alleged complaint. The papers from my Senate years that I donated to the University of Delaware do not contain personnel files.”
The allegations against Mr Biden are particularly troubling for the Democratic Party, who are trying to pitch their candidate as the principled candidate opposed to Mr Trump.
Mr Biden has pledged to pick a woman as a running mate, and the allegation has left those thought to be in contention in a tough spot.
Former Democratic National Committee Chairwoman Donna Brazile said: “The campaign has issued statements, but he hasn’t issued any statements in his own voice.
“It’s not helping, it’s just damaging — not only to the person who has come forward, but it’s also damaging the candidate.”
The November contest between Biden and Trump will be the first presidential race in the #MeToo era, which has led to numerous women coming forward with allegations of sexual assault.
Mr Trump has been accused of assault and unwanted touching by numerous women, something he denies.
Speaking about the allegation for the first time on Thursday, Trump said Biden “should respond”.