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Donald Trump.

Real-estate magnate Donald Trump fired off multiple furious tweets Wednesday night after a crude remark was used against him on Fox News.

Rich Lowry, the editor of the conservative magazine National Review, said the Republican presidential front-runner was attacking rival Carly Fiorina because she emasculated him at last week's presidential debate.

"Part of what's going on here is that last debate. Let's be honest: Carly cut his balls off with the precision of a surgeon, and he knows it," Lowry said during a Fox News interview, according to video posted by Mediaite.

Host Megyn Kelly was shocked.

"What did you just say?!" Kelly said. "You can't say that."

But Trump, who has fiercely feuded with both Fox News and Kelly, wasn't satisfied with her admonishment.

He trashed Lowry on Twitter as "incompetent" and "clueless," demanded an apology, and suggested that the Federal Communications Commission should fine Lowry as a result.

Trump's tweets:

During a Thursday interview on CNN, Trump offered still more criticism. He said Lowry "used words that were so unbelievable," "made a total fool of himself," and had a "nervous breakdown on television."

But Lowry refused to back down.

In a series of his own Wednesday night tweets, he continued to taunt Trump. He noted that Trump frequently bragged about not being politically correct and that the businessman used a "boorish insult" against Fiorina, the former Hewlett-Packard CEO who confronted him at last week's CNN debate for mocking her face.

Lowry's response:

It also doesn't seem likely that the FCC will fine Lowry. CNN's Brian Stelter reported that the commission "occasionally fines broadcast networks for indecency but has no power to sanction cable channels like Fox News."

The tiff is only the latest salvo in what has become an all-out war between Trump and Fox, in which two apparent cease-fires were reached in August.

Earlier Wednesday, Trump announced he would no longer appear on the network because it had been so unfair to him, singling out Kelly in particular. A Fox representative responded by saying that when "coverage doesn't go his way, he engages in personal attacks on our anchors and hosts, which has grown stale and tiresome."

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