Ahead of a planned speech, Robert F Kennedy Jr’s campaign team said in court documents that he is endorsing Donald Trump for president.
Mr Kennedy’s independent campaign also requested that he be removed from the Pennsylvania ballot, though it was not immediately clear that he was officially dropping out of the race.
He was about to speak in Arizona “about the present historical moment and his path forward,” according to his campaign.
Hours later, Mr Trump will hold a rally in neighbouring Glendale.
Mr Trump’s campaign has teased that he will be joined by “a special guest”, though neither campaign responded to messages about whether Mr Kennedy would be that guest.
Mr Kennedy withdrew from the ballot in Arizona on Thursday, less than a week after he submitted well more than the required number of signatures to appear on the ballot.
But his critics raised questions about the validity of some of the signatures, and the involvement of a pro-Kennedy super PAC to collect them risked potentially running afoul of rules against coordination between candidates and independent political groups.
A year ago, some would have thought it inconceivable that Mr Kennedy — a member of the most storied family in Democratic politics — would work with Mr Trump to keep a Democrat out of the White House.
Even in recent months, Mr Kennedy has accused Mr Trump of betraying his followers, while Mr Trump has criticised Mr Kennedy as “the most radical left candidate in the race”.
But the two campaigns have ramped up their compliments to each other and engaged in behind-the-scenes discussions in recent weeks, according to those familiar with the efforts.
Both campaigns have spent months accusing Democrats of weaponising the legal system for their own benefit.
And both have hinted publicly that they could be open to joining forces, with the shared goal of limiting the election chances of Democratic presidential nominee Kamala Harris.
Mr Trump told CNN on Tuesday that he would “love” an endorsement from Mr Kennedy, whom he called a “brilliant guy”.
He also said he would “certainly” be open to Mr Kennedy playing a role in his administration if he drops out and endorses him.
Mr Kennedy’s running mate, Nicole Shanahan, also openly suggested on a podcast this week that his campaign might “walk away right now and join forces with Donald Trump”.
While she clarified that she is not personally in talks with Mr Trump, she entertained the idea that Mr Kennedy could join Mr Trump’s administration as secretary of the Department of Health and Human Services.
“I think that Bobby in a role like that would be excellent,” Ms Shanahan said. “I fully support it. I have high hopes.”
The scheduled remarks by Mr Kennedy, a son of former Attorney General Robert F Kennedy and a nephew of former President John F Kennedy, come as his campaign’s momentum has slipped.
He first entered the 2024 presidential race as a Democrat but left the party last fall to run as an independent.
He built an unusually strong base for a third-party bid, fuelled in part by anti-establishment voters and vaccine sceptics who have followed his anti-vaccine work since the pandemic.
But he has since faced strained campaign finances and mounting legal challenges, including a recent ruling from a New York judge that he should not appear on the ballot in the state because he listed a “sham” address on nominating petitions.
Recent polls put his support in the mid-single digits. And it is unclear if he would get even that in a general election, since third-party candidates frequently do not live up to their early poll numbers when voters actually cast their ballots.
For Mr Trump, Friday will mark the end of a week’s worth of battleground state visits in which he has sought to draw attention away from Democrats’ celebration of Ms Harris’ presidential nomination in Chicago.
He travelled to Pennsylvania, Michigan, North Carolina and Arizona’s US-Mexico border for events focused on his policy proposals on the economy, crime and safety, national security and the border.
He will close out the week Friday with stops in Las Vegas and Glendale.
