Former President Donald Trump attacked pop star Taylor Swift on Sunday, less than a week after the musician endorsed Vice President Kamala Harris.

“I hate Taylor Swift!” Trump posted in capital letters on Truth Social, the website of the Trump Media and Technology Group.

Swift endorsed Harris in an Instagram post on Tuesday, shortly after the presidential debate between the two major party candidates.

“I consider her a calm, gifted leader and believe we can accomplish so much more in this country when we are led by calm, not chaos,” Swift wrote in the post. She also captioned the post “childless cat lady,” a reference to remarks made by Republican vice presidential candidate JD Vance about Democratic women.

Trump had previously shared fake, artificial intelligence-generated images on social media that showed Swift and her fans supporting him. Swift cited these types of images as the reason she made her support public.

The Harris-Walz campaign responded to Trump’s post on Sunday with a statement that included many references to Swift’s music.

“Donald Trump’s week of whining and spreading conspiracy theories has caused voters on both sides of the aisle to forget his existence,” campaign spokeswoman Sarafina Chitika said in the statement. “The American people want to move beyond the chaos and division of the Trump era, leave the void of Trump’s broken promises behind, and start anew with the election of Vice President Harris to ensure America’s future of opportunity lasts long.”

It’s unclear what impact celebrity endorsements will have on the presidential race, even for figures as popular as Swift. About a day after her endorsement of Harris, her post had driven more than 300,000 visitors to Vote.gov, a government website that directs users to state-specific voting information.