Donald Trump proposes debating Kamala Harris on Sept. 4 in Pennsylvania on Fox News

Former President Donald Trump said on social media that he has agreed with Fox News to debate Vice President Kamala Harris on Sept. 4. Harris promptly rejected the idea and her campaign said Trump should “stop playing games.”

The debate would take place in Pennsylvania before a live audience, moderated by Fox News anchors Bret Baier and Martha MacCallum, Trump said on his Truth Social media site late Friday night. The Republican nominee said the precise location of the debate was yet to be determined.

Harris responded Saturday on X, formerly Twitter: “It’s interesting how ‘any time, any place’ becomes “one specific time, one specific safe space. I’ll be there on September 10th, like he agreed to. I hope to see him there.”

Before President Joe Biden dropped his bid for reelection, he and Trump had agreed to debate on ABC on Sept. 10. Biden endorsed Harris, who is now the presumptive Democratic nominee.

Trump had been noncommittal about debating Harris. And a debate on Fox is hardly certain.

On Saturday, the Harris campaign said the former president “is running scared and trying to back out of the debate he already agreed to and running straight to Fox News to bail him out. He needs to stop playing games and show up to the debate he already committed to on Sept 10.”

The campaign said the vice president “will be there one way or the other” to speak to a national primetime audience.

“We’re happy to discuss further debates after the one both campaigns have already agreed to. Mr. Anytime, Anywhere, Anyplace should have no problem with that unless he’s too scared to show up on the 10th.”

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In a subsequent post, Trump said, “Kamala Harris doesn’t have the mental capacity to do a REAL Debate against me, scheduled for September 4th in Pennsylvania. ... I’ll see her on September 4th or, I won’t see her at all.”

A Fox News debate would be the second of the presidential election campaign, and the first pitting Trump against Harris. Biden’s poor performance in the first debate, on June 27, helped end his reelection campaign.

David Plouffe, a former senior adviser to President Barack Obama who now advises the Harris campaign, called Trump “cowardly” for “backing out of the debate he agreed to.”

“He seems only comfortable in a cocoon,” Plouffe said on X, “asking his happy place Fox to host a Trump rally and call it a debate. Maybe he can only handle debating someone his own age.”