Former President Donald Trump has declared himself very much not a Swiftie.

Days after Taylor Swift endorsed Kamala Harris for president, the Republican presidential nominee expressed his distaste for the mega pop star — in all caps.

“I HATE TAYLOR SWIFT!” Trump wrote in a post on Truth Social on Sunday.

After the debate between Harris and Trump had wrapped on Tuesday night, Swift threw her support behind the Democratic vice president.

“She fights for the rights and causes I believe need a warrior to champion them,” Swift wrote to her more than 280 million followers on Instagram. “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 said she was driven to publicize her "actual plans for this election as a voter” after she became aware that Trump had pushed misinformation suggesting that he was getting her vote.

Last month, Trump shared an AI-generated image of Swift in an Uncle Sam outfit giving a fake endorsement to his campaign, along with other images promoting the idea that he’d won over some of her fanbase. “I accept,” he said in posting the images. He's since denied knowing anything about the images.

Swift’s past endorsements and political statements have a record of boosting civic engagement. Swift first made her political views known ahead of the 2018 midterms, voicing her support for LGBTQIA rights and gender and racial equality, when her endorsement of two Tennessee congressional candidates prompted tens of thousands of people to register to vote.

Swift’s recent Instagram endorsement drove more than 300,000 visitors to the voter registration website Vote.gov, NPR reported.

While Swift may have sway, it’s not clear how much. An ABC News/Ipsos poll released on Sunday found Swift's endorsement had "little impact" on whether respondents would be more likely to vote for Harris.

And celebrity endorsements also have the potential to backfire. The celebrity could steal all the attention away from the candidate, or their fans may not share the same politics.

On Wednesday, the day after the debate, Trump shrugged off Swift’s endorsement of Harris in an interview on the Fox News show Fox & Friends.

“I was not a Taylor Swift fan,” Trump said.

“It was just a question of time. She couldn’t possibly endorse Biden,” he added. “But she’s a very liberal person. She seems to always endorse a Democrat and she’ll probably pay a price for it in the marketplace.”

That night, at MTV’s Video Music Awards, Swift urged people to register to vote while accepting the award for video of the year, after a fan vote.

“Please register to vote for something else that’s very important: our presidential election,” Swift said.