US Senate candidate challenged by abortion accuser before runoff
Former football star Herschel Walker is running for one of Georgia's two seats in the US Senate, vying to unseat Democrat Raphael Warnock(AFP)

A US woman who says anti-abortion Republican Senate candidate Herschel Walker pressured her into terminating her pregnancy has challenged him to deny her story face-to-face, before next month's runoff election in Georgia.

Walker has previously denied even knowing the woman, who is one of two to come forward alleging they had intimate relations with the former American football star and that he paid for abortions after impregnating them.

The challenge comes as the one-time Dallas Cowboys star prepares to face off again with Democratic Senator Raphael Warnock, after neither earned a simple majority of votes in Georgia to win the seat in this month's midterm election.

"Herschel, I never thought you would deny knowing me, or our relationship," said the anonymous accuser at a Los Angeles press conference Tuesday.

"Are you really willing to do anything -- including lying to the voters in Georgia -- to become a senator?"

"Do you have the guts to meet with me in person, in public, look me in the eye, and tell me to my face that you don't know me?"

The woman says she began her relationship with Walker, who was married, in November 1987, and learned she was pregnant in April 1993.

She alleges that Walker drove her back to an abortion clinic after she initially went to get the procedure alone but hesitated.

The Trump-endorsed Walker has made an anti-abortion stance a key plank of his campaign for one of Georgia's two seats in the US Senate.

At Tuesday's press conference, celebrity attorney Gloria Allred presented additional evidence of the alleged relationship, including handwritten letters and diary entries.

Allred played a voicemail audio message in which a man claimed to be Walker is heard saying: "This is your stud farm calling, you big sex puppy."

Walker's campaign has been beset by controversy, including allegations of past domestic abuse, an exaggerated resume, and fathering children outside of his marriage.

Last month, a different woman came forward to accuse Walker of paying for her 2009 abortion. Walker has denied both allegations.

The Republicans have already failed to win the Senate, but a defeat for Walker in the tight race on December 6 would see the Democrats extend their razor-thin majority in the upper house of Congress.

Allred challenged Walker to meet his accuser in a public place "at a time and date of your choosing prior to December 6 to respond to the evidence we have presented."

"If you don't agree... we think it is fair for the voters in Georgia to conclude that Jane Doe is telling the truth and that you are not being transparent and honest with the voters in Georgia."

The anonymous accuser added: "I think it's up to the voters of Georgia to decide who they want to represent them, and who to believe."

Walker did not immediately respond.

© Agence France-Presse