The Republican Senate candidate Herschel Walker, a staunch anti-abortion politician accused by a former girlfriend of encouraging and paying for her abortion in 2009, used his only debate against the Democratic senator Raphael Warnock on Friday to deny his previous support for an outright national abortion ban.

The former college football and NFL star, who is endorsed by Donald Trump, was asked about his support for “a complete ban on a national level”. He said the moderator misstated his position. That contradicted statements made repeatedly on the campaign trail, including in July when Walker said it was “a problem” that no national ban existed.

Walker also answered an attack from Warnock about his past claims about being a law enforcement officer by producing what he said was a police badge.

Warnock said: “You can support police officers as I’ve done … while at the same time holding police officers, like all professions, accountable. One thing I have not done, I’ve never pretended to be a police officer. And I’ve never, I’ve never threatened a shootout with the police.”

Saying “I have to respond to that”, Walker produced his badge.

Walker has never been a trained law enforcement officer, though he has law enforcement endorsements.

As Walker brandished his badge, the debate moderator said: “Mr Walker, Mr Walker – excuse me, Mr Walker. I need to let you know, Mr Walker, you are very well aware of the rules tonight. And you have a prop that is not allowed. Sir, I asked you to put that prop away.”

Walker did not do so immediately.

The moderator said: “Excuse me, sir. You’re very well aware of the rules, aren’t you?”

Walker said: “Well, let’s talk about the truth.”

Walker’s apparent battle with the truth over abortion has become a theme of the midterm elections. On Friday, he said his position was the same as Georgia’s state law, a so-called heartbeat bill that bans abortion at six weeks, before many women know they are pregnant. That law went into effect this year after the US supreme court overturned the right to abortion.

The heated exchange on abortion was one of many that highlighted stark differences between Warnock and Walker. Warnock did not directly bring up the allegation about Walker paying for an abortion, leaving moderators to elicit a flat denial. Walker blasted Warnock for being a Baptist pastor who supports abortion rights.

“Instead of aborting those babies, why aren’t you baptizing those babies?” he said.

Warnock said “God gave us a choice and I respect the right of women to make a decision”, adding that Walker “wants to arrogate more power to politicians than God has”.

Warnock and his fellow Democrat Jon Ossoff won their Senate seats in a January 2021 special election, two months after Joe Biden beat Trump in Georgia by fewer than 12,000 votes. It was the first time in two decades Democrats won federal elections in the state, raising questions about whether Warnock can win again as Biden’s popularity falls.

In-person voting begins on Monday. The outcome will help determine control of the Senate, currently split 50-50.

Onstage, Walker claimed Warnock was a Biden puppet, saying the election was about what they “had done to you and your family” in an inflationary economy. Warnock said the election was about “who is ready to represent Georgia”.

Walker blamed Warnock and Biden for inflation but offered little when asked what he would do to fix it. Walker said the first step was “getting back” to energy independence rather than depending “on our enemies”. The US had never been free from fossil fuel imports, some from countries such as Russia.

Warnock highlighted Biden’s Inflation Reduction Act, focusing on provisions he sponsored capping insulin and other healthcare costs, the extension of the child tax credit and infrastructure provisions he shepherded with Republicans. He offered few specifics about further steps.

Warnock declined to say if Biden, nearing 80, should seek re-election in 2024. Walker deviated from Trump by saying Biden won legitimately in 2020. But he said he would support Trump if he ran in 2024. Both Walker and Warnock said they would accept the outcome of their election.

Both men discussed their personal lives. Recent reporting by the Daily Beast disclosed records of an abortion receipt and personal check from Walker to a woman who said he paid for her abortion. Walker’s denials have continued even after the woman identified herself as the mother of one of his four children. Walker acknowledged three children publicly for the first time only after Beast reporting.

Other reports have detailed how Walker has exaggerated academic achievements, business success and philanthropic activities, as well as accusations he threatened the life of his ex-wife beyond details acknowledged in a 2008 memoir. In perhaps his most effective debate move, Warnock alluded to such stories.

“We will see time and time again tonight, as we’ve always seen, that my opponent has a problem with the truth,” said Warnock.

Dismissing reports that a foundation tied to Ebenezer Baptist Church, where he is senior pastor, had evicted tenants from real-estate holdings, Warnock said Walker was trying to “sully the name of Martin Luther King’s church”.

Walker pointed to his memoir, in which he detailed a diagnosis of dissociative personality disorder. Walker said he had “been transparent” and “continue[d] to get help if I need help, but I don’t need any help. I’m doing well. I’m ready to lead today.”

Walker declined three debates typical in Georgia campaigns. The Savannah debate did not include the libertarian Chase Oliver, who did not meet a polling threshold. Warnock will meet Oliver in a Sunday debate sponsored by the Atlanta Press Club. Walker will be represented by an empty podium.