Republican vice presidential nominee JD Vance on Thursday said he agreed to debate with Democratic nominee Tim Walz on October 1.
Mr Walz first agreed to the CBS News-hosted matchup on Wednesday evening.
“See you on October 1, JD,” Mr Walz, who is Kamala Harris's running mate, wrote in a post on X.
A campaign official told CBS that Mr Walz “looks forward to debating JD Vance – if he shows up”. The two vice presidential hopefuls have been trading barbs since they were named as their presidential candidates' running mates.
The date was one of four proposed by the US television network for a vice presidential debate.
Mr Vance, who is Donald Trump's running mate, upped the stakes and said he would meet Mr Walz on September 18 as well.
"The American people deserve as many debates as possible, which is why president Trump has challenged Kamala to three of them already," he said in a post on X.
"Not only do I accept the CBS debate on October 1, I accept the CNN debate on September 18th as well. I look forward to seeing you at both!"
The Harris-Walz campaign declined the request for a second vice presidential debate.
Michael Tyler, communications director for the campaign, said "the debate about debates is over".
Mr Tyler said both the Trump and Harris campaigns had agreed on three debates, which include two presidential and one vice presidential debates.
He stated that a second presidential debate was contingent on whether Mr Trump "actually shows up on September 10" and then "the American people will have another opportunity to see" Ms Harris and Mr Trump in October.
"Voters deserve to see the candidates for the highest office in the land share their competing visions for our future," Mr Tyler said.
Mr Vance, a senator from Ohio known for his memoir Hillbilly Elegy about growing up in poverty in Appalachia, has accused Mr Walz of lying about his military record.
Writing on X on Tuesday, Mr Vance also thanked Mr Walz for his service but said he “shouldn't have lied about it”.
“You shouldn’t have said you went to war when you didn’t. Nor should you have said that you didn’t know your unit was going to Iraq. Happy to discuss more in a debate.”
The Minnesota National Guard, however, confirmed to The National that Mr Walz retired after 24 years of service on May 16, 2005 – about two months before his 125th Field Artillery battalion received an alert order to go to Iraq.
Mr Walz, meanwhile, has stuck to the criticism that first thrust him into the spotlight: calling Republicans “weird”.
“I just have to say it. You know it. You feel it. These guys are creepy and, yes, just weird as hell,” Mr Walz told supporters at a rally in Philadelphia.
