Former President Donald Trump declared late Friday that he was dropping out of an ABC News debate scheduled for Sept. 10 and presented a counterproposal to Vice President Kamala Harris, his presumptive opponent, to face off on Fox News six days earlier.

The change, which Trump announced on his social media site, Truth Social, raised objections from the Harris campaign and appeared to throw a potential showdown between the rivals into question.

According to Trump’s social media post, the Fox News debate would take place at a to-be-determined location in Pennsylvania, one of the most consequential battleground states, and be moderated by Bret Baier and Martha MacCallum.

The Harris campaign Saturday declined to commit to the Fox News debate and said it was still planning on a Sept. 10 debate hosted by ABC.

“Donald Trump 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,” Michael Tyler, the Harris campaign’s communications director, said in a statement.

He added: “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.”

A spokesperson for Fox News did not respond to questions.

Trump said the Fox News debate would have a live audience; the June 27 debate between President Joe Biden and Trump was hosted by CNN in an empty venue. Though both campaigns agreed to the format of the first debate, Trump had bemoaned the lack of a crowd. He added the rules would be similar to the CNN debate, though he did not specify which rules. That debate included mic cuts to prevent interruption.

Trump also said he is “prepared to accept” Harris as the Democrats’ new candidate after characterizing her ascendancy as a “coup.”