Joe Biden says he believes he has never acted inappropriately after a former political candidate claimed he gave her a "big slow kiss" on the back of her head in 2014.
Barack Obama's former vice-president has moved to defuse the threatened controversy as he considers whether to seek the Democratic nomination to run against Republican US President Donald Trump in the 2020 contest for the White House.
Lucy Flores, a former Nevada state representative and the 2014 Democratic nominee for Nevada lieutenant governor, said the alleged incident at a rally in Las Vegas had left her feeling "uneasy, gross, and confused" and that it was "demeaning and disrespectful".
Responding in a statement, Mr Biden said: "In my many years on the campaign trail and in public life, I have offered countless handshakes, hugs, expressions of affection, support and comfort.
"And not once – never – did I believe I acted inappropriately. If it is suggested I did so, I will listen respectfully. But it was never my intention.
"I may not recall these moments the same way, and I may be surprised at what I hear.
"But we have arrived at an important time when women feel they can and should relate their experiences, and men should pay attention. And I will."
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He added: "I will also remain the strongest advocate I can be for the rights of women.
"I will fight to build on the work I've done in my career to end violence against women and ensure women are treated with the equality they deserve.
"I will continue to surround myself with trusted women advisers who challenge me to see different perspectives than my own.
"And I will continue to speak out on these vitally important issues where there is much more progress to be made and crucial fights that must be waged and won."