Independent US presidential candidate Robert F. Kennedy Jr. says he is suspending his campaign and endorsing former President and Republican nominee Donald Trump.

He made the announcement in a speech in Arizona on Friday.

Kennedy is a nephew of former US President John F. Kennedy. He announced his candidacy last October.

Kennedy said he was suspending his campaign and not ending it. He said his name will remain on the ballot in most states.

He added that in his heart, he no longer believes he has a realistic path to electoral victory.

Kennedy said he has talked with Trump. He said they continue to have very serious differences on many issues and approaches, but are aligned on other key issues.

Trump indicated on Tuesday that he would consider appointing Kennedy to a key role in his administration if he dropped out of the race and the former president is reelected.

A poll by political information site Real Clear Politics shows that as of Thursday, Vice President and Democratic nominee Kamala Harris had 46.4 percent support, Trump 44.4 percent and Kennedy 5 percent.

Attention is focused on what impact Kennedy's suspension will have on the election as he was expected to attract voters from both the Democratic and Republican parties.