RFK Jr is the son of the late Attorney General and Senator Robert Kennedy and the nephew of President John F Kennedy, both heavyweights in Democratic party history.
ADVERTISEMENTRobert F Kennedy Jr suspended his independent presidential bid and endorsed Donald Trump in a widely expected move in this year's race for the White House.
Kennedy Jr said in a speech on Friday that he would seek to remove his name from the ballot in battleground states because he believed his presence in the race would help Democratic rival, Kamala Harris.
"Many months ago, I promised the American people that I would withdraw from the race if I became a spoiler. A spoiler is someone who will alter the outcome of the election but has no chance of winning. In my heart, I no longer believe that I have a realistic path to electoral victory in the face of this relentless systematic censorship and media control," he said.
"Our polling consistently showed that by staying on the ballot in the battleground states, I would likely hand the election over to the Democrats, with whom I disagree on the most existential issues: censorship, war, and chronic disease."
RFK Jr said his supporters can continue to support him in most states, where they are unlikely to sway the outcome.
He took steps to withdraw his candidacy in at least two states, Arizona and Pennsylvania, earlier this week.
He said the move followed conversations with Trump over the past few weeks and told reporters he is now throwing his "support to President Trump."
Before the speech, his campaign had said in a Pennsylvania court filing that he would endorse Trump for president. However, a spokesperson for RFK Jr said the court filing had been made in error.
RFK Jr is the son of the late Attorney General and Senator Robert Kennedy and the nephew of President John F Kennedy, both heavyweights in Democratic party history.
He acknowledged his decision to endorse Trump had caused tension with his immediate family.
Five of Kennedy's family members issued a statement on Friday calling his support for Trump "a sad ending to a sad story" and reiterated their support for Harris.
While campaigning in Las Vegas, Trump said it was a "great honour" to receive Kennedy’s endorsement.
"I want to thank Bobby, that was very nice. That was really very nice. That's big. He's a great guy, respected by everybody," he said.
RFK Jr and Trump campaigns have ramped up their compliments of each other in recent weeks. Both campaigns have spent months accusing Democrats of weaponising the legal system for their own benefit.
Both hinted publicly that they could be open to joining forces to limit Harris' chances.
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