CNN refused to air a Trump campaign ad that pushes misleading claims about Joe Biden's role in the ouster of a Ukrainian prosecutor and suggests the network's anchors are the Democrats' "media lapdogs," The Daily Beast reports. The Trump campaign said the ad is "factually accurate."

Why it matters: This isn't the first time CNN has determined that the Trump campaign crossed its red line on advertising political content. When CNN stopped running an ad that vilified immigrants in 2018, NBC and Fox later followed suit.

The big picture: Trump tweeted the 30-second spot titled "Biden Corruption" last week. The ad claims that Biden "promised Ukraine $1 billion if they fired the prosecutor investigating his son's company. ... But when President Trump asks Ukraine to investigate corruption, the Democrats want to impeach him."

The ad then shows a montage of cable news hosts including CNN's Chris Cuomo, Don Lemon and correspondent Jim Acosta, before adding: "And their media lapdogs fall in line. They lost the election, now they want to steal this one."

Context: Trump's allegations that the media is biased against him have been a hallmark of his political career. On Wednesday, Trump concluded a press conference with the president of Finland by claiming that U.S. democracy would be better off if the media were honest, singling out "the CNNs of the world, who are corrupt people."

What they're saying: "CNN is rejecting the ad, as it does not meet our advertising standards,” a spokesperson told The Daily Beast. "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.”

Trump campaign spokesperson Tim Murtaugh responded:

“Everything in that ad is factually accurate. Biden threatened to withhold $1 billion from Ukraine if they did not fire the prosecutor looking into the company Hunter Biden worked for. It’s a fact.”

"CNN spends all day protecting Joe Biden in their programming, so it’s not surprising that they’re shielding him from truthful advertising too, and then talking to other media outlets about it. Our ad is entirely accurate and was reviewed by counsel, and CNN wouldn’t even describe to us what they found objectionable. This isn’t a cable news channel anymore, it’s a Democrat public relations firm.”

Go deeper ... Fact check: What Joe and Hunter Biden actually did in Ukraine

Editor's note: This story has been corrected to show the Trump campaign spokesperson is Tim Murtaugh and updated with additional comment from Trump campaign.