Donald Trump continued to attack Fox News anchor Megyn Kelly on Saturday, a day after the network fought back against the Republican frontrunner, defending Kelly’s work and criticizing Trump’s “extreme, sick obsession with her.”

Fox’s response followed an escalation of Trump’s insults on Friday, when he called for a boycott of her show.

“Everybody should boycott the [Megyn Kelly] show,” he wrote on Twitter. “Never worth watching. Always a hit on Trump! She is sick, & the most overrated person on tv.”

Trump has kept up attacks on Kelly throughout his campaign, insulting her after she questioned him about his rhetoric toward women at a debate and later refusing to participate in another debate when Fox wouldn’t remove her as moderator. Kelly has largely not responded.

“Donald Trump’s vitriolic attacks against Megyn Kelly and his extreme, sick obsession with her is beneath the dignity of a presidential candidate who wants to occupy the highest office in the land,” said Irena Briganti, a spokeswoman for the network on Friday, the New York Times reported.

“Megyn is an exemplary journalist and one of the leading anchors in America — we’re extremely proud of her phenomenal work and continue to fully support her throughout every day of Trump’s endless barrage of crude and sexist verbal assaults. As the mother of three young children, with a successful law career and the second highest rated show in cable news, it’s especially deplorable for her to be repeatedly abused just for doing her job.”

Trump responded on Saturday by bringing the conversation back to the ratings, as his campaign joined the attack on the show.

“Despite the fact he wants nothing to do with her and will not appear on her show due to her extremely biased reporting, much of the program is about him anyway on a nightly basis,” Trump spokeswoman Hope Hicks said in a statement Friday, according to the Times. “Unlike Megyn Kelly, who resorts to putting out statements via FOX News, Mr. Trump will continue to defend himself against the inordinate amount of unfair and inaccurate coverage he receives on her second-rate show each night.”

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Write to Katie Reilly at Katie.Reilly@time.com.