PHILADELPHIA (AP) — Anti-vaccine activist Robert F. Kennedy Jr. is expected to announce Monday that he will drop his Democratic bid for president and run as an independent or third-party candidate, adding a new wrinkle to a 2024 race currently heading toward a rematch between President Joe Biden and former President Donald Trump.

Kennedy's campaign has teased the announcement in the days leading up to a Monday afternoon speech in Philadelphia. In a recent video, Kennedy said there is corruption "in the leadership of both political parties" and said he wants to "rewrite the assumptions and change the habits of American politics."

The video came shortly after Mediaite reported he planned to launch an independent bid.

A member of one of America's most famous Democratic families, the 69-year-old Kennedy was running a long-shot Democratic primary bid but has better favorability ratings among Republicans. It's unclear whether GOP support would translate to a general election when Kennedy would also be running against Trump, the early front-runner for the GOP presidential nomination. Allies of both Biden, a Democrat, and Trump have at times questioned whether Kennedy would be a spoiler against their candidate.

Biden's allies so far have dismissed Kennedy's primary campaign as unserious. Asked for comment on his potential independent run, a Democratic National Committee spokesman responded with an eye roll emoji.

Monday's announcement comes less than a week after the progressive activist Cornel West abandoned his Green Party bid in favor of an independent White House run. Meanwhile, the centrist group No Labels is actively securing ballot access for a yet-to-be-named candidate.

Kennedy has spent weeks accusing the DNC of "rigging" the party's primary against him and threatening that he might need to consider alternatives.

In campaign emails and videos, he blasted the DNC's decision not to host debates between Biden and other candidates and railed against the committee's plan to give South Carolina rather than Iowa or New Hampshire the leadoff spot on the primary calendar this election cycle.

"If they jam me, I'm going to look at every option," he said in September at a New Hampshire barbecue held by Republican former Sen. Scott Brown.

Far-right and anti-vaccine influencers close to Kennedy also have sent strong signals on social media suggesting he should or will leave the Democratic Party. Last month, Joseph Mercola, an influential anti-vaccine doctor who is allied with Kennedy, ran a poll on X, formerly known as Twitter, asking if Kennedy should quit the party.

While Kennedy has long identified as a Democrat and frequently invokes his late father, Sen. Robert F. Kennedy, and his uncle President John F. Kennedy on the campaign trail, he has built close relationships with far-right figures in recent years. He appeared on a channel run by the Sandy Hook conspiracy theorist Alex Jones and headlined a stop on the ReAwaken America Tour, the Christian nationalist road show put together by Trump's former national security adviser Michael Flynn.

Polls show far more Republicans than Democrats have a favorable opinion of Kennedy. He also has gained support from some far-right conservatives for his fringe views, including his vocal distrust of COVID-19 vaccines, which studies have shown are safe and effective against severe disease and death.

Kennedy's anti-vaccine organization, Children's Health Defense, currently has a lawsuit pending against a number of news organizations, among them The Associated Press, accusing them of violating antitrust laws by taking action to identify misinformation, including about COVID-19 and COVID-19 vaccines. Kennedy took leave from the group when he announced his run for president but is listed as one of its attorneys in the lawsuit.

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Associated Press writers Michelle Smith and Will Weissert contributed to this report.

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