Robert F Kennedy Jr claims Trump had asked him to be running mate

<span>Robert F Kennedy Jr waves to supporters during a campaign event on Saturday in West Des Moines, Iowa.</span><span>Photograph: Charlie Neibergall/AP</span>
Robert F Kennedy Jr waves to supporters during a campaign event on Saturday in West Des Moines, Iowa.Photograph: Charlie Neibergall/AP

Robert F Kennedy Jr, the prominent conspiracy theorist and independent presidential candidate, claimed on Monday he had turned down an offer from Donald Trump to be his running mate for the White House.

The assertion followed the launch earlier in the day of a website attacking Kennedy, published by a pro-Trump political action committee called Make America Great Again Inc (Maga Inc).

Accusing Kennedy, 70, of being a “leftist radical”, the vitriolic website attempts to highlight what it says are his extremist liberal positions, including supporting a 70% rate of income tax and pledging he would sign an assault weapons ban.

Related: ‘He can help Trump win’: US groups take on RFK Jr after No Labels stands down

Poking fun at the famous political dynasty’s fondness for middle initials, shared by assassinated relatives including his uncle John F Kennedy, and father Robert F Kennedy, the website is titled “Radical F-ing Kennedy”.

In response, Kennedy, who has blended outlandish theories about Covid-19 with a long history of racism, antisemitism and xenophobia, posted on X, formerly Twitter, to make his own claims.

“President Trump calls me an ultra-left radical. I’m soooo liberal that his emissaries asked me to be his VP. I respectfully declined the offer,” he wrote.

“I am against President Trump, and President Biden can’t win. Judging by his new website, it looks like President Trump knows who actually can beat him.”

An email from Maga Inc sent to reporters later on Monday accused Kennedy of a “defensive and emotional” response to the website launch, but did not address the claim he had turned down an offer to be the vice-presidential pick of Trump, the presumptive Republican nominee.

While Kennedy, a former Democrat, has no chance of winning the presidency, analysts say his campaign, and those of other third-party candidates, can be an effective spoiler for Joe Biden’s chances of returning to the White House.

Last month Kennedy named Nicole Shanahan, a tech attorney and wealthy philanthropist, as his own running mate, introducing her at a rally in Oakland, California, her home town.

His choice of the 38-year-old was widely seen as an attempt to attract millennial and gen Z voters he believes are uninspired by the November rematch between Biden, 81, and Trump, 77. Polling from Quinnipiac in February suggested Kennedy could receive as much as 15% of the vote.

Trump attacked Kennedy “as the most radical left candidate in the race” in a rambling post to his Truth Social network platform last week, Mediaite reported.

“If I were a Democrat, I’d vote for RFK Jr every single time over Biden, because he’s frankly more in line with Democrats,” Trump wrote.

“He is Crooked Joe Biden’s political opponent, not mine.”