Robert F Kennedy, nephew of assassinated former president John F Kennedy (JFK) and the son of Bobby Kennedy, who was killed while running for the White House, has thrown his support behind Republican nominee Donald Trump, promoting criticism from his own family.

The Kennedy family said Robert F. Kennedy Jr's endorsement of Donald Trump in the US presidential race, was a "betrayal" of their values.

Kennedy, also known as RFK Jr, announced he was suspending his independent campaign for the presidency to lend his support to the Republican candidate in certain states.

"In about 10 battleground states where my presence would be a spoiler, I'm going to remove my name, and I've already started the process,"

Kennedy said during a news conference in Arizona.

RFK Jr, whose father Robert F Kennedy was assassinated as he ran for president back in 1968, said the Democratic Party was no longer "champions of the constitution" and had departed "dramatically" from the "core values" he grew up with.

Kennedy, 70, cited free speech, the war in Ukraine and "a war on our children" as among the reasons he would try to remove his name from the ballot in battleground states.

"These are the principal causes that persuaded me to leave the Democratic Party and run as an independent, and now to throw my support to President Trump," he said.

RFK Jr hit out at the media and the Democrats during his announcement, while saying his campaign team had "pulled off a miracle" by making him a presidential candidate.

"You showed everyone democracy is still possible here," he said. "Today I'm here to tell you I will not allow your efforts to go to waste."

Kennedy added he believed that in an "honest system" he would have won the election.

In response to RFK Jr's announcement, his brothers and sisters shared a statement, saying: "We want an America filled with hope and bound together by a shared vision of a brighter future, a future defined by individual freedom, economic promise and national pride.

"We believe in Harris and Walz.

"Our brother Bobby's decision to endorse Trump today is a betrayal of the values that our father and our family hold most dear.

"It is a sad ending to a sad story."

Trump, who is running for president for a third time after a successful and an unsuccessful bid in 2016 and 2020 respectively, reacted to the endorsement saying: "It's an honour".