Donald Trump today pledged to “fight back” against Megyn Kelly, dismissing Fox News’ charge that the man who would be president has a “sick obsession” with the network’s primetime star.

On Friday, Fox News took its defense of Kelly to a whole new level, blasting Trump for his “vitriolic attacks against Megyn Kelly and his extreme, sick obsession with her” which the news division said “is beneath the dignity of a presidential candidate who wants to occupy the highest office in the land.” That came hours after Trump, as he has many times since announcing his candidacy, took off after Kelly on Twitter, alerting “everybody” to boycott her show because it’s “Always a hit on Trump!” and describing her as “sick, & the most overrated person on tv.”

Trump responded to Fox today with this:

Trump’s been going at it since August, when Kelly opened the first GOP debate with a question to the reality-TV star as to whether he thought a person who’d called women “‘fat pigs,’ ‘dogs,’ ‘’slobs’ and ‘disgusting animals’”  had the proper temperament of a president.

The presidential candidate responded the morning after the debate with what some believe was a menstruation joke, telling CNN’s Don Lemon that when Kelly had asked that question, “You could see there was blood coming out of her eyes, blood coming out of her – wherever.”

Trump boycotted FNC’s next GOP debate, initially citing Kelly, who was again booked to co-moderate, as his reason.