“Though the Trump campaign is prepared to fabricate outright lies, your station’s airwaves should not be used to disseminate them,” Schultz wrote. “We are putting you on notice about the absolute falsity of the advertisement’s claims, and we expect that you will reject it. Please consider this letter a standing request that you reject any advertisement containing similar claims, regardless whether the Trump campaign or a third-party group seeks to place it.”

“We are not in the business of censoring ads from candidates on either side of the aisle,” a Fox News spokesperson said in a statement to POLITICO. “Vice President Joe Biden has a standing invitation to appear on any of our platforms.”

CNN said Thursday that it is refusing to air the “Biden Corruption” ad, according to The Daily Beast. In addition to targeting Biden, the ad also characters CNN’s Don Lemon, Chris Cuomo and Jim Acosta, and MSNBC’s Rachel Maddow as “media lapdogs.”

“CNN is rejecting the ad, as it does not meet our advertising standards,” a network spokesperson said. “Specifically, in addition to disparaging CNN and its journalists, the ad makes assertions that have been proven demonstrably false by various news outlets, including CNN.”

The Biden campaign has aggressively pushed back on Ukraine-related reports in an attempt to not let allegations fester in the media likes those which dogged Hillary Clinton’s 2016 campaign.

On Sunday, the campaign urged executives and hosts at CNN, Fox, MSNBC, NBC, ABC and CBS to no longer book Rudy Giuliani, accusing President Donald Trump’s lawyer of spreading “false, debunked conspiracy theories” on behalf of his client.