Days after pop megastar Taylor Swift endorsed Kamala Harris, Donald Trump has kicked the Swiftie nest by very presidentially posting on his Truth Social media account, in all-caps: “I HATE TAYLOR SWIFT!”

Despite his team and surrogates trying to shrug off the endorsement, following last week’s Trump-Harris debate, Trump is clearly sore that Swift informed her 284 million Instagram followers that she planned to vote for Harris.

Swift's post has drawn over nine million "likes", and fuels speculation it could boost the Democrat ticket.

Trump had posted AI images suggesting Swift had endorsed him for president, clearly showing that he coveted her endorsement. One image showed Swift dressed as Uncle Sam, accompanied with the words, “Taylor wants you to vote for Donald Trump.”

In her Instagram statement, Swift said Trump’s AI posts influenced her decision to announce her endorsement.

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

Trump had initially dismissed Swift's endorsement of his rival by simply saying he was "not a Taylor fan" and that the superstar would “probably pay a price” for her decision.

“It was just a question of time,” said Trump. “She couldn’t possibly endorse Biden… 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.”

Now, the former president has declared war over Swift and her Swifties. His four-word statement has gone viral and the reaction has been... swift.

The Harris campaign teased him with a (very) pun-heavy press release referencing Swift's songs:

"Mr Not-at-all Fine has spent this week working through his feelings, whining about his Champagne Problems, and spending exactly none of his time addressing the issues facing the American people," the statement says.

It adds: "His rambling, yelling and constant conspiracy theories have many asking if The Man is 'too emotional' to be president. Call it What You Want, but it's Nothing New for the Smallest Man Who Ever Lived."

Referencing his chaotic and rambling presidential debate performance, it adds that the Trump campaign can't "Shake it Off as the Bad Blood between Trump, his running mate, and his own party boils".

Star Wars actor Mark Hamill wrote: “#ILoveTaylorSwift” as a reaction to a post captioned "Real men praise Taylor Swift for her talent”.

Several celebrities like Mia Farrow, Flavor Flav and Bradley Whitford also posted the same statement, alongside author Stephen King: “I love Taylor Swift. Her music makes me happy. End of story.”

Other celebrities who have endorsed Kamala Harris include Beyoncé, George Clooney, Spike Lee, Olivia Rodrigo, Charli XCX, Jamie Lee Curtis, John Legend, Bon Iver, Matt Damon and Lin-Manuel Miranda, the last two announcing they will attend fundraiser in New York City this month —for which tickets are listed at $25,000 per person—to support the Democratic ticket, according to Bloomberg.

Taylor Swift also recently used her acceptance speech for the Video of the Year at the MTV Video Music Awards to urge viewers to register to vote.

While many debate whether a celebrity endorsement can make a meaningful difference, there have been reports that Swift’s backing of Harris has caused a “500 per cent” increase in voter registration.

According to CNN correspondent Elizabeth Wagmeister, nearly half a million people were directed to the registration site Vote.gov from Swift’s Instagram page – up from around 30,000 site visitors a day.

Data firm TargetSmart’s senior adviser Tom Bonier has stated that Swift’s endorsement has directly led to a “400 per cent or 500 per cent increase” in voter registration – resulting in 9000 to 10,000 registrations per hour.

Bonier added that the spike is “unlike anything” he’s ever seen.

The presidential election is set to be held on 5 November.