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BOSTON (AP) — Anti-vaccine activist Robert F. Kennedy Jr. launched his longshot bid to challenge President Joe Biden for the Democratic nomination next year.

Kennedy, a member of one of the country’s most famous political families who has in recent years been linked to some far-right figures, kicked off his campaign in Boston on Wednesday and likened his campaign to the American revolution.

“My mission over the next 18 months of this campaign and throughout my presidency will be to end the corrupt merger of state and corporate power that is threatening now to impose a new kind of corporate feudalism in our country,” Kennedy said.

Self-help author Marianne Williamson is also running for the Democratic nomination. Biden has said he’s planning on running again but has not formally announced a campaign. He’s expected to have a glide path to the nomination, with much of the Democratic establishment behind him.

Kennedy, a nephew of President John F. Kennedy and the son of his slain brother Robert F. Kennedy, repeatedly referenced both of them during his lengthy speech Wednesday.

Kennedy Jr. was once known most as an environmental lawyer who worked on issues such as clean water. But over the past nearly two decades, he’s become one of the leading voices of the anti-vaccine movement. His work has been described by members of his own family and public health experts as misleading and dangerous.

His efforts intensified after the pandemic and development of the COVID-19 vaccine, and an AP investigation in 2021 showed he had linked up with anti-democratic figures and other groups. He has appeared at events pushing the lie that the 2020 presidential election was stolen and with people who cheered or downplayed the insurrection at the U.S. Capitol on Jan. 6, 2021.

A photo posted on Instagram showed Kennedy backstage at a July 2021 Reawaken America event with former President Donald Trump’s ally Roger Stone, former National Security Adviser Michael Flynn and anti-vaccine profiteer Charlene Bollinger. All three have promoted the lie about the 2020 election being stolen.

Kennedy has been a guest on Infowars, the channel run by conspiracy theorist Alex Jones, and on the “War Room” podcast hosted by longtime Trump ally Steve Bannon, where he promoted his bestselling 2021 book, “The Real Anthony Fauci,” in which he accused the U.S.’s top infectious disease doctor of participating in “a historic coup d’etat against Western democracy.”

The AP documented how Kennedy and his anti-vaccine group, Children’s Health Defense, had capitalized on the COVID-19 pandemic – raking in funding and followers in the U.S. and abroad, and doubling its revenue from 2019 to 2020. Researchers have found that the group is among the most influential spreaders of anti-vaccine misinformation, and the AP found traffic to its website had soared.

In the second year of the pandemic, Children’s Health Defense continued its huge growth, according to a more recent filing with charity regulators in California. Revenue more than doubled from $7 million in 2020 to $16 million in 2021.

Facebook and Instagram removed the accounts of Children’s Health Defense for spreading misinformation.

Kennedy has repeatedly invoked Nazis and the Holocaust when talking about measures aimed at mitigating the spread of COVID-19, such as mask requirements and vaccine mandates. He has apologized for some of those comments, including when he suggested that people in 2022 were worse off than Anne Frank, the teenager who died in a Nazi concentration camp after hiding with her family in a secret annex in an Amsterdam house for two years.