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(NewsNation) — Minutes after the end of the first debate between former President Donald Trump and Vice President Kamala Harris, Taylor Swift endorsed the Democratic candidate in a long Instagram post.

“Like many of you, I watched the debate tonight,” Swift wrote. “I will be casting my vote for Kamala Harris and Tim Walz in the 2024 Presidential Election. I’m voting for @kamalaharris because she fights for the rights and causes I believe need a warrior to champion them.”

The endorsement came as a surprise to the Harris campaign, a campaign official confirmed to NewsNation. Harris exited a watch party with Second Gentleman Doug Emhoff to a Swift song.

The singer said that she needed “to be very transparent about my actual plans for this election as a voter” after AI-generated photos of her endorsing Trump’s presidential run were posted to his site.

“It really conjured up my fears around AI, and the dangers of spreading misinformation,” Swift, one of the music industry’s biggest stars wrote. “The simplest way to combat misinformation is with the truth.”

Just before the Democratic National Convention kicked off, Trump reposted an image of Swift in an Uncle Sam outfit and accepted her endorsement for his campaign, which she had never given.

Swift, who remains on her world tour, made no endorsements until this point. Given her influence and millions of fans, Swift has often become a trending political topic during election years.

Swift has a dedicated following among young women, a key demographic in the November election.

“I was so heartened and impressed by her selection of running mate @timwalz, who has been standing up for LGBTQ+ rights, IVF, and a woman’s right to her own body for decades,” Swift wrote on Instagram.

She included a picture of herself holding a cat and signed the message “Childless Cat Lady,” a reference to comments made by Sen. JD Vance, Trump’s running mate.

In 2020, she supported President Joe Biden, writing a month before the election that she was going to be cheering for then-vice presidential nominee Harris, this year’s Democratic nominee, in her debate against then-Vice President Mike Pence. She also was openly critical of Trump ahead of the 2020 election, saying he had stoked “the fires of white supremacy and racism.”

Fox News’ Jeanine Pirro earlier this year warned Swift not to “get involved in politics.” Fox News’ Sean Hannity urged her to “think twice” about backing Biden when he was running for reelection. And Vivek Ramaswamy, a former GOP presidential candidate and vocal Trump supporter, called Swift and her NFL star boyfriend Travis Kelce “an artificially culturally propped-up couple” who may make “a major presidential endorsement” this fall.

“I’ve done my research, and I’ve made my choice. Your research is all yours to do, and the choice is yours to make. I also want to say, especially to first time voters: Remember that in order to vote, you have to be registered! I also find it’s much easier to vote early. I’ll link where to register and find early voting dates and info in my story,” Swift concluded in her post.

The Associated Press contributed to this report.