CNN has informed the largest outside group supporting President Trump’s reelection that it will not run one of its new ads, saying the ad is false because it warns Democratic nominee Joe Biden will raise taxes on the middle class and implies that Speaker Nancy Pelosi (D-Calif.) supports socialist policies.

The ad, from America First Action (AFA), says Biden “sided with socialists,” while showing pictures of Pelosi and Rep. Alexandria Ocasio-Cortez (D-N.Y.).

The narrator of the ad also warns that Biden will “raise taxes on the middle class" and that "his liberal agenda will cost millions of jobs.”

America First Action says the ad has been approved to run on ABC, AMC, Cooking, CBS, Comcast, DIY, Discovery, ESPN, Food Network, Fox, HGTV, History, Lifetime and The Weather Channel.

But in an email, an account executive at Warner Media said the clearance team rejected it.

“WarnerMedia Commercial Clearance has not accepted America First Action's advertisement ‘We Are America' for its networks as the ad does not meet its commercial clearance standards,” the email states. “Specifically, the ad asserts that Biden will raise taxes on the middle class. That claim is not adequately substantiated and has been judged false by independent fact-checkers. The advertisement also mischaracterizes Nancy Pelosi as a socialist.”

In addition to CNN, the ad will not be able to run on other Turner Broadcast stations, including TNT, TBS and TCM.

The Hill has reached out to CNN for comment.

In a letter to lawyers at Warner Media, an attorney representing AFA accused the media company of censoring normal political speech that is “at the very least a matter worthy of debate.”

“While AFA’s opponents are, of course, permitted to purchase air time to try to rebut AFA’s claims, it is not the job of your network to censor a statement that is factually supported and relates to an important issue in the upcoming election,” wrote Stephen Kenny of Jones Day. “Indeed, every other cable network is currently airing AFA’s ad. If you continue to decline to air the ad, please let us know why the factual support outlined above is insufficient.”

Biden has said he’ll repeal the Trump tax cuts but he says he’ll do it in a way that ensures people making less than $400,000 don’t see their taxes go up.

Trump and Republicans say that if Democrats take control of Congress and the White House they’ll raise taxes on everyone. They also say that even if Biden only raises taxes on corporations and the wealthiest, that middle-class workers will get saddled with indirect new costs associated with those taxes.

The Kenny letter points to analyses done by the Tax Foundation, Tax Policy Center, American Enterprise Institute, the Committee for a Responsible Federal Budget, the University of Pennsylvania and others that have concluded that some middle-class households will see lower investment returns and wages because of the tax hikes on corporations.

“These are important policy debates that should be aired in the public square in advance of the election,” Kenny wrote.

And Kenny argued that using the term “socialist” to describe Pelosi is “often used in political discourse to signify generally a set of left-leaning political positions.”

"Pelosi favors tuition-free community college, universal subsidized child care, and universal health care," he wrote. "The ad does not imply she advocates for a more aggressive strain of 'socialism' whereby the government controls all means of production. Instead, the ad describes accurately where her positions on key issues place her on the political spectrum.”

He pointed to a recent episode of "Reliable Sources" on CNN in which host Brian Stelter and guest Jason Stanley “engaged in a lengthy discussion comparing President Trump to a fascist leader and ‘Trumpism’ to fascism.”