NASHVILLE (AP) — Music superstar Taylor Swift has officially launched her Kamala Harris era.

Shortly after the Democratic nominee and former President Donald Trump finished their first, and likely only, presidential debate Tuesday evening, Swift, who is nearing the end of her "Eras Tour," released a lengthy Instagram post announcing her support for Harris — as well as a link to a voter registration website.

She included a photo of herself holding her cat Benjamin Button, and she signed the message "Childless Cat Lady — a reference to 2021 comments made by JD Vance, Trump's running mate, about how women without children don't really have a stake in the country's future.

The endorsement isn't the first time Swift has waded into politics, but it ends months of speculation over whether she'd pick a side in this year's presidential tilt. Here's what to know:

Why did Swift pick Harris?

In her Instagram post, Swift said she would be voting for Harris because Harris "fights for the rights and causes I believe need a warrior to champion them."

"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," she wrote.

Swift also said her endorsement of Harris was partially prompted by Trump's decision to post artificial intelligence-generated pictures suggesting she had endorsed him. One showed Swift dressed as Uncle Sam, and the text said "Taylor wants YOU to VOTE for DONALD TRUMP."

Trump's posts "brought me to the conclusion that I need to be very transparent about my actual plans for this election as a voter," Swift wrote.

In response, Trump told "Fox & Friends" on Wednesday that Swift is "a very liberal person" who "seems to always endorse a Democrat and she'll probably pay a price in the marketplace."

Did the Harris campaign know the endorsement was coming?

Swift did not coordinate her endorsement with the Harris campaign, according to two senior campaign officials who spoke on the condition of anonymity to discuss the campaign's thinking about Swift. Her running mate, Minnesota Gov. Tim Walz, appeared surprised by the news when presented with it during an interview with MSNBC.

However, although Harris' team says Swift's post wasn't coordinated, they were prepared for the eventuality and within minutes reposted Swift's Instagram message across the campaign's channels and released a Swift-themed Harris-Walz friendship bracelet on its store that quickly sold out.

Who did Swift endorse in 2020?

Swift supported Democrat Joe Biden, even posting a photo on social media of her holding "Biden 2020" cookies and saying she cheered for Harris in her debate against then-Vice President Mike Pence.

Swift also was openly critical of Trump, saying he had stoked "the fires of white supremacy and racism."

When did Swift first start weighing into politics?

Swift first broke her long-standing refusal to discuss politics in 2018 by throwing her support behind Tennessee's Democratic Senate candidate at the time, Phil Bredesen, who was running against Republican Marsha Blackburn.

It was her criticism of Blackburn that stood out in her endorsement, where Swift – who is registered to vote in Tennessee -- slammed the Republican's opposition to certain LGBTQ+ rights and her vote against the Reauthorization of the Violence Against Women Act in 2013.

"In the past I've been reluctant to publicly voice my political opinions, but due to several events in my life and in the world in the past two years, I feel very differently about that now," Swift wrote on Instagram at the time.

Blackburn eventually won the election in conservative Tennessee, but the endorsement nevertheless solidified Swift as an influential political force.

What prompted the change?

The 2020 Netflix documentary, "Miss Americana," captured several dramatic turning points for Swift, but one of the most revealing involved behind-the-scenes conversations she was having with her family before speaking out against Blackburn in the 2018 Senate race.

Her father warned against it, citing a potential economic impact and security concerns. And her publicist said Trump might come after her.

"I'm saying right now that this is something I know is right," she told her team. "I need to be on the right side of history."

In the film, Swift said her desire to wade into politics was sparked after she successfully countersued a Denver radio DJ who she said groped her during a meet-and-greet before a concert.

"It's not that I want to step into this," Swift said in the film. "It's just that I can't not at this point. Something is different in my life, completely and unchangeably different since the sexual assault trial last year. No man in my organization or in my family will ever understand what that was like."

How influential are celebrity endorsements?

Swift's endorsement don't always translate into wins. In 2018, Blackburn won by a comfortable margin. At the time, AP VoteCast found that among Tennessee voters that year, 55% of Democrats and just 19% of Republicans said they had a favorable opinion of Swift.

Notably, Swift is originally from Pennsylvania, a crucial battleground that will be critical for either presidential candidate to their chances of winning the presidency. Yet it's unclear how much sway she might hold among its voters.

While she's popular nationwide, her popularity is especially strong among Democrats. An October 2023 Fox News poll found that 55% of voters overall, including 68% of Democrats, said they had a favorable view of Swift. Republicans were divided, with 43% having a favorable opinion and 45% an unfavorable one.

Swift could make history at the MTV Video Music Awards on Wednesday, where she could become the most-awarded musician. The event is known for encouraging young people to register to vote, and should Swift attend, she could reiterate her support for Harris.

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Associated Press writer Zeke Miller in Washington contributed to this report.