Taylor Swift endorsed Kamala Harris for president moments after the end of Tuesday night's presidential debate against Donald Trump.

The pop star made her announcement in an Instagram post signed as "Childless Cat Lady" - a reference to comments by Trump's running mate JD Vance.

Her post, breaking her silence on the 2024 vote, explained: "I'm voting for @kamalaharris because she fights for the rights and causes I believe need a warrior to champion them."

Within 24 hours of her announcement, nearly 340,000 people had visited the voter registration website, vote.gov, using a custom link created and shared by Swift.

Swift, who also backed Democratic President Joe Biden in 2020, called Harris a "steady-handed, gifted leader".

She added: "I believe we can accomplish so much more in this country if we are led by calm and not chaos."

Swift's text was accompanied by a photo of her with a cat. Her "Childless Cat Lady" comment was a nod to remarks made in 2021 by Vance, who is Trump's candidate for vice-president.

Vance, the Ohio senator, has faced a backlash for a clip in which he called several prominent Democrats - including Harris - "a bunch of childless cat ladies who are miserable at their own lives". He recently said his comments were "sarcastic".

Swift went on to compliment Harris's choice of vice-presidential candidate, Minnesota Governor Tim Walz, who she said had been "been standing up for LGBTQ+ rights, IVF, and a woman's right to her own body for decades".

The singer said she was in part motivated to share her voting decision with the public after an AI image of her falsely endorsing Trump was posted on his website.

"It really conjured up my fears around AI, and the dangers of spreading misinformation," she said. "It brought me to the conclusion that I need to be very transparent about my actual plans for this election as a voter."

Trump went on to embrace the fake images in a post that sparked a backlash among Swift's fans - or Swifties - who accused Trump of spreading misinformation.

In response to Swift's endorsement of Harris, Trump told Fox News that "was not a Taylor Swift fan."

He called her a "very liberal person" and said that she will "pay the price for it in the marketplace."

Noting Swift's political past, one academic who studies the intersection of media and politics suggested that the endorsement was unlikely to move the needle in Harris's favour.

"No surprise at all, she endorsed Biden and Harris in 2020 so we already knew her politics," said Lauren Rosewarne, a University of Melbourne professor.

Swift's endorsement could impact voter registration, Ms Rosewarne told the BBC. But because her fan-base skews young and female - and that is already the Harris supporter base - her endorsement may not have a big impact come November.

The singer has 283 million followers on Instagram. Her endorsement has received more than 4.5 million likes on Instagram less than three hours after she posted it.

In her post, Swift urged first-time voters to register and said she would post a link with more voting information on her page.

"I've done my research, and I've made my choice," she said. "Your research is all yours to do, and the choice is yours to make."