President Trump on Monday fired back at Taylor Swift over her endorsement of Democrats in next month’s midterms, declaring that his enthusiasm for the pop megastar’s music has waned by “about 25 percent.”

Swift, whose stance on politics had until recently been a blank space, caused a stir Sunday night with an Instagram post in which she announced that she plans to vote for Tennessee Democrats Phil Bredesen for the Senate and Jim Cooper for the House this November.

Bredesen is facing Rep. Marsha Blackburn (R) in the Senate race. Trump headlined a rally last week for Blackburn, who polls show is locked in a neck-and-neck race with Bredesen for the seat of Sen. Bob Corker (R), who is retiring.

“Well, Marsha Blackburn is doing a very good job in Tennessee,” Trump said Monday night before entering the White House after returning from an event in Florida. “She’s leading now substantially, which she should. She’s a tremendous woman. I’m sure Taylor Swift doesn’t know anything about her. Let’s say that I like Taylor’s music about 25 percent less now, okay?”

Swift singled out Blackburn for criticism in her Instagram post, taking aim at her record on LGBT rights and her vote against reauthorizing the Violence Against Women Act, among other issues.

“Running for Senate in the state of Tennessee is a woman named Marsha Blackburn,” Swift said in the post. “As much as I have in the past and would like to continue voting for women in office, I cannot support Marsha Blackburn. Her voting record in Congress appalls and terrifies me.”

Just how big a T-Swift fan Trump was to begin with remains unclear. The president has previously declared himself a fan of artists as varied as Frank Sinatra, Eminem and Steve Reich, as well as of Kanye West, himself a Trump megafan.

Bredesen, for his part, touted Swift’s endorsement in a tweet Monday evening.

“.@VoteMarsha, look what you made her do,” Bredesen wrote. “@taylorswift13 doesn’t like your little games and she wants Tennesseans to know that you’ve been in the swamp long enough. It’s time for some fresh air up in Washington.”