Former president Donald Trump lashed out at 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 all caps on Truth Social, the website owned by the Trump Media & Technology Group.

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

“I think she is a steady-handed, gifted leader and I believe we can accomplish so much more in this country if we are led by calm and not chaos,” Swift wrote in the post. She also signed the caption as “childless cat lady,” a reference to remarks about Democratic women made by Republican vice presidential nominee JD Vance.

Trump had previously shared fake artificial intelligence-generated images on social media that showed Swift and her fans supporting him. Swift cited those types of images as a reason she went public with her endorsement.

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

“Donald Trump’s week of whining and spouting conspiracy theories has voters on both sides of the aisle ready to forget that he existed,” campaign spokesperson Sarafina Chitika said in the statement. “The American people want to be out of the woods of the chaos and division of the Trump era, leave behind the blank space of Trump’s broken promises, and begin again by electing Vice President Harris to ensure America’s future of opportunity is long lived.”

It is unclear how much impact celebrity endorsements will have on the presidential race, even for figures as popular as Swift. Roughly 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.