Dozens of bogus testimonies from American actors, singers and athletes about Republican nominee Trump and his Democratic rival Kamala Harris have proliferated on social media ahead of the November election, researchers say, many of them enabled by artificial intelligence image generators.

The fake endorsements and brushoffs, which come as platforms such as the Elon Musk-owned X knock down many of the guardrails against misinformation, have prompted concern over their potential to manipulate voters as the race to the White House heats up.

Last month, Trump shared doctored images showing Swift threw her support behind his campaign, apparently seeking to tap into the pop singer's mega star power to sway voters.

The photos -- including some that Hany Farid, a digital forensics expert at the University of California, Berkeley, said bore the hallmarks of AI-generated images -- suggested the pop star and her fans, popularly known as Swifties, backed Trump's campaign.

What made Trump's mash-up on Truth Social "particularly devious" was its combination of real and fake imagery, Farid told AFP.

Last week, Swift endorsed Harris and her running mate Tim Walz, calling the current vice president a "steady-handed, gifted leader."

The singer, who has hundreds of millions of followers on platforms including Instagram and TikTok, said those manipulated images of her motivated her to speak up as they "conjured up my fears around AI, and the dangers of spreading misinformation."

Following her announcement, Trump fired a missive on Truth Social saying: "I HATE TAYLOR SWIFT!"