WASHINGTON (AP) — Vice President Kamala Harris and Republican JD Vance on Tuesday had their first chat since the Ohio senator became the GOP vice presidential nominee, but the two sides are still working on terms for participating in a debate, according to three people familiar with the matter.

Harris has agreed to a debate on CBS News on either July 23 or Aug. 13. Two months ago, former President Donald Trump agreed to those same dates, or one later in the calendar, on behalf of his then-unidentified running mate — but for a debate on Fox News, which Biden's team has indicated it would reject.

The people, who spoke on the condition of anonymity to discuss internal conversations about the debate, said there had been no progress at bridging the disagreements on the network partner and format, but they expect discussions to begin now that Trump has selected Vance, a first-term senator from Ohio.

"Obviously, we want to debate Vice President Harris because it's important for the American people to see the contrast," Vance told Newsmax on Tuesday evening.

Harris, in her congratulatory voicemail to Vance on his selection on Monday, urged him to accept the CBS debate, according to one of the people familiar with the discussions. Vance returned Harris' call on Tuesday and the pair exchanged pleasantries, that person said. A second person said they shared a desire to debate, but didn't discuss specifics.

Vance told Newsmax that Harris was "was very gracious, very cordial" on the call.

Last month's debate disaster for President Joe Biden, Saturday's attempted assassination of Trump, and the ages of both men atop their respective tickets could raise the stakes for the running mates' potential faceoff.

"Vice President Harris is prepared to debate JD Vance," Biden campaign spokesman TJ Ducklo told reporters Monday after Vance was added to the GOP ticket. "We have accepted the proposal from CBS News — I think as folks are aware — to participate in that debate, and we feel very good."

Massachusetts Sen. Elizabeth Warren told reporters on a Biden campaign call, "The V.P. will take it to JD Vance."

"The debate is going to have two parts to it," she continued. "It's how strong our vice president is and how good her economic issues are. I'm looking forward to this debate."

Finding someone would could perform well against Harris was among Trump's considerations as he assessed the field of potential candidates. And on that measure Vance stood out.

Vance had first captured Trump's attention during his campaign for the Senate in 2022 — a viciously nasty primary in which the candidates often seemed to be competing more for Trump's endorsement than for Republican votes.

.As Trump was weighing the field, the candidates gathered for a raucous debate in which two of Vance's rivals had a near-physical altercation on stage.

The debate became intense almost as soon as it began, as former state Treasurer Josh Mandel attacked investment banker Mike Gibbons' business dealings in his opening remarks. Soon, the two were standing face to face on the debate stage, shouting at each other as the moderator tried to keep their argument from further escalating.

But instead of jumping into the fray, Vance tried to be the bigger man.

"Sit down. Come on," he said, sitting in a row with the remaining candidates. "This is ridiculous."

Vance, a military veteran, also slammed Mandel as "disgraceful" for using the Marine Corps as a "political football," drawing loud applause from the crowd. "What a joke," he said.

The performance caught Trump's attention and helped Vance win the former president's crucial endorsement.

Trump's campaign did not respond Tuesday when asked whether Vance would agree to one of the two proposed CBS dates.

Trump had said he hoped Harris and his eventual running mate would meet at Virginia State University, which is where Fox proposed holding its event.

The university was originally scheduled to host a debate put on by the nonpartisan Commission on Presidential Debates, and it would have been the first time a historically Black college or university hosted one.

Virginia's two senators, Democrats Tim Kaine and Mark Warner, have urged the candidates to still hold a debate at the school.

CBS would host the debate in one of the network's studios, which is the Biden team's preference.

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Colvin reported from Milwaukee. AP writers Seung Min Kim, Michelle L. Price and Jonathan J. Cooper contributed.