Trump campaign refuses to commit to a VP debate before August's Democratic convention

Former President Donald Trump's campaign said Wednesday that it won’t agree to proposed dates for a vice presidential debate until at least the Democratic National Convention, which is scheduled to begin Aug. 19.

Brian Hughes, a senior adviser to the Trump campaign, signaled that it wouldn’t make sense to solidify a debate date yet for the vice presidential contenders because of the still-growing group of Democrats calling on President Joe Biden to withdraw from the race. He suggested that Vice President Kamala Harris could ultimately be named the party’s presidential nominee.

“We don’t know who the Democrat nominee for Vice President is going to be, so we can’t lock in a date before their convention. To do so would be unfair to Gavin Newsom, JB Pritzker, Gretchen Whitmer, or whoever Kamala Harris picks as her running mate,” Hughes said in a statement, citing the Democratic governors of California, Illinois and Michigan.

In mid-May, Harris accepted an invitation from CBS News to debate on either July 23 or Aug. 13. A Biden campaign official said Wednesday that CBS has since offered, and Harris has accepted, another potential date of Aug. 12. The Trump campaign had not agreed to the CBS debate, but it did agree to a vice presidential debate hosted by Fox News.

Trump named Sen. JD Vance of Ohio to be his running mate Monday. Vance is set to accept the Republican nomination for vice president Wednesday night at the Republican National Convention in Milwaukee.

Harris' team lashed out at the Trump campaign Wednesday, with her communications director, Brian Fallon, saying Trump was the one whose campaign said he would debate "anytime, any place."

“Now suddenly right after a damning new leak showing his support for a nationwide abortion ban, Vance is backing off a debate against Vice President Harris, who has spent the last two years prosecuting the case on behalf of reproductive freedom," Fallon said.

“This debate has been discussed for two months now," he added. "If JD Vance is unwilling to defend the Trump-Vance record on the debate stage, he should just say so.”

Biden has said emphatically that he is not exiting the presidential race despite his poor debate performance in June and increasing fears among Democratic members of Congress that he would lose to Trump in November.

As an increasing number of Democratic lawmakers have called on Biden to drop out, Harris has emerged as his likely successor, since she would be first in line to potentially inherit his sizable campaign war chest.

Rep. Adam Schiff, a prominent Democrat running for the Senate in California, called on Biden on Wednesday to drop out of the race. Earlier this month, Schiff told NBC News' "Meet the Press" that Harris “very well could win overwhelmingly” if Biden dropped out and would be a “phenomenal president.”

As other lawmakers have issued similar calls for Biden to pass the torch, Trump and his allies have in turn been intensifying their attacks on Harris and framing the election as a referendum on her, as well.

Former GOP presidential candidate Nikki Haley took aim at Harris in her Republican National Convention speech Tuesday night.

"For more than a year, I said a vote for Joe Biden is a vote for President Kamala Harris," she said. "After seeing the debate, everyone knows it’s true. If we have four more years of Biden or a single day of Harris, our country will be badly worse off. For the sake of our nation, we have to go with Donald Trump."

This article was originally published on NBCNews.com