Independent US presidential candidate Robert F Kennedy Jr said on Friday he would suspend his campaign, and endorsed Republican Donald Trump, likely ending a presidential bid that he began as a Democrat trading on one of the most famous names in American politics.

His campaign indicated that he feared staying in the race would siphon support from former President Trump, who is locked in a tight contest with Democratic Vice President Kamala Harris ahead of the November 5 election.

An environmental lawyer, anti-vaccine activist and son and nephew of two titans of Democratic politics who were assassinated during the turbulent 1960s, Kennedy entered the race in April 2023 as a challenger to President Joe Biden for the Democratic nomination.

With voters at the time turned off by both the aging Biden and the legally embattled Trump, interest in Kennedy soared. He shifted his plans and decided to run as an independent, and a November 2023 Reuters/Ipsos poll showed Kennedy drawing the support of 20 percent of Americans in a three-way race with Biden and Trump.

He ran a high-profile advertisement during the February 2024 Super Bowl that invoked his father, US Senator Robert F. Kennedy, and uncle, US President John F Kennedy, and drew outrage from much of his high-profile family, who condemned his campaign.

In exchange for endorsing Trump, Kennedy was hoping for a job in a potential Trump administration, a super PAC supporting Kennedy said on Wednesday. He also wanted Trump to allow his political movement to continue in some fashion, which could include staying on the ballot in some states.

Kennedy said this month in a video posted online that he dumped a dead bear in New York City's Central Park a decade ago and staged it to look like a bike had hit it. He proclaimed he had "so many skeletons in my closet" after a former family babysitter accused him of sexual assault.

He denied that a picture of him posing with the barbecued carcass of a large animal belonged to a canine.

And then there was the brain worm. Kennedy had a parasite in his brain more than a decade ago, but has since fully recovered, a fact unearthed by the New York Times and confirmed by the campaign.

Those stories prompted ridicule from late-night talk show hosts. (Reuters)