Robert F Kennedy Jr, the scion of the Democratic Kennedy family whose independent presidential campaign threatened to draw votes from both Republicans and Democrats, has suspended his campaign and endorsed Donald Trump.

Kennedy said he will be removing his name from the ballot in critical swing states, but he will remain on the ballot in other states and some voters could still cast ballots for him.

Kennedy, whose uncle, John F Kennedy, and father, Robert F Kennedy, were both assassinated, announced that he was running against Joe Biden for the Democratic nomination in April 2023.

He left that race last October however, warning that under the two-party system the US is “cycling from despair to rage and back to despair”, and ran as an independent.

Kennedy’s campaign was seen as a threat to both Harris and Trump, but in the past few months Kennedy was dogged by controversies. He was accused of assaulting a former babysitter, it emerged that Kennedy believed that part of his brain had been eaten by a worm, and in early August he admitted to having staged a bizarre bicycle hit-and-run incident with a dead bear cub in a New York City park.

As his election bid floundered, Kennedy reportedly made overtures to the Harris campaign in August to discuss dropping out and endorsing her in exchange for a job in her administration, while he was also courted by Trump in July.

Having initially hovered at about 10% in national polling, Kennedy’s popularity dropped amid the scandals, with the 70-year-old averaging about half of that in August. The campaign struggled to raise money, with just $3.9m cash-on-hand at the end of July, and debts of $3.5m. Politico reported that Kennedy spent more than $7m in July – more than the $5.6m it raised.

Both Democrats and Republicans watched Kennedy’s campaign closely, however, mindful that his mix of vaccine skepticism, hardline policies on the border, and ties to the most famous Democratic family in politics, could draw votes in key swing states.

Kennedy, as a former Democrat, was initially seen as more of a threat to Democrats winning the presidential election, but in recent months he was seen to be drawing more votes from Trump, something his running mate, Nicole Shanahan, admitted on Tuesday.

“There’s two options that we’re looking at,” Shanahan told the Impact Theory podcast.

“One is staying in, forming that new party, but we run the risk of a Kamala Harris and [Tim] Walz presidency, because we draw votes from Trump. Or we walk away right now and join forces with Donald Trump. We walk away from that and we explain to our base why we’re making this decision.”

There has been evidence that Trump did see Kennedy as a threat.

A video posted online on 16 July showed a phone call between Trump and Kennedy where Trump appeared to offer an opportunity for the pair to work together in the future. The video came after reports – denied by Kennedy – that he might drop out and endorse Trump.

Kennedy’s apparent efforts to meet with Harris to discuss endorsing her in exchange for a possible cabinet secretary position were snubbed by the Harris campaign.

His run for president has been controversial. Recently Kennedy responded to an allegation that he sexually assaulted an employee by stating: “I am not a church boy,” while in July 2023, a video surfaced of Kennedy making false claims that Covid-19 was “ethnically targeted” to attack Black people and white people while sparing Ashkenazi Jews and Chinese people.

Last year Kennedy claimed that wifi causes “leaky brain” and has linked antidepressants to school shootings. In 2023 he also claimed that chemicals in water were making children transgender, while Kennedy has longstanding, and wrong, beliefs about apparently any and all vaccines.