REUTERS/Aaron Josefczyk
Fox News host Megyn Kelly at the first Fox Republican primary debate last year.
On Saturday morning, Trump wrote on Twitter that because of Kelly's "conflict of interest," she "should not be allowed to be a moderator of the next debate."
It wasn't immediately clear what Kelly had done to earn Trump's latest attack, but she did interview National Review's editor, Rich Lowry, the night before.
The influential conservative magazine launched an all-out effort to take down Trump, who responded by trashing the "failing" magazine. During her interview with Lowry, Kelly said it was "amusing" that Trump had hailed National Review as a "true conservative voice" in April 2015.
Business Insider reached out to Fox News for comment. But it would seem unlikely that the network would consider shaking up its talent lineup for next Thursday's debate, which is also set to be moderated by Fox anchors Bret Baier and Chris Wallace.
Indeed, Fox announced last December that Kelly would be a moderator even though Trump had been furiously attacking her since August, when she moderated the first Fox debate. Kelly infuriated Trump at the time by asking a rather pointed question about disparaging comments he's made about women's looks.
Since then, Trump has waged an on-again-off-again war against Fox News, with many of his attacks aimed at Kelly. Trump drew backlash after twice promoting tweets calling Kelly a "bimbo." He also once criticized Kelly with an infamous comment that many interpreted as a crude reference to menstruation, though Trump claimed he was being misinterpreted.
Trump has had at least a small amount of apparent success, however, after complaining about debate moderators.
ABC severed its February debate partnership with the Union Leader after Trump relentlessly attacked the New Hampshire newspaper for running a front-page editorial criticizing him. And the National Review was booted from its partnership on another February debate after its anti-Trump advocacy this week.