Since Robert F. Kennedy Jr. launched his campaign challenging President Biden for the 2024 Democratic presidential nomination, he has given hours of interviews to podcasts, magazines and TV networks. He paints a dark, conspiratorial picture of the world, bristling with debunked theories, misleading claims and outright falsehoods.

Wi-Fi causes cancer and "leaky brain," Kennedy told podcaster Joe Rogan last month. Antidepressants are to blame for school shootings, he mused during an appearance with Twitter CEO Elon Musk. Chemicals in the water supply could turn children transgender, he told right-wing Canadian psychologist and podcaster Jordan Peterson, echoing a false assertion made by serial fabulist Alex Jones. AIDS may not be caused by HIV, he has suggested multiple times.

There's no credible evidence for any of these assertions or for Kennedy's longest-running false claims: that vaccines cause autism and are more harmful than the diseases they're designed to protect against.

Yet Kennedy is building a campaign for the highest office around these conspiracy theories and the idea that fact-checking or criticizing them amounts to censorship. His throughline is the bedrock conspiratorial premise that "they" (the government, pharmaceutical companies, the media) are lying to you — but that he is telling the truth.

"This is what happens when you censor somebody for 18 years," Kennedy told a cheering crowd at his April campaign kickoff in Boston. "They shouldn't have shut me up that long, 'cause now I'm really going to let loose on them for the next 18 months."

It's an apparent bet that the political, cultural and media dynamics that elevated Kennedy and the anti-vaccination movement during the COVID-19 pandemic can similarly propel him to the White House.

The Kennedy campaign did not respond to NPR's questions for this story.

Allegations of censorship and collusion

Kennedy isn't the first American politician to actively advance conspiracy theories. Donald Trump promoted birtherism and, later, the Big Lie that the 2020 election was stolen from him. Richard Nixon blamed Jews for orchestrating communist plots and controlling the government.

But what stands out in Kennedy's case is the sheer volume of what he has asserted over the years, from his insistence that Republicans stole the 2004 election to his claims that 5G networks are being used for mass surveillance to his belief that the CIA assassinated his uncle.

In 2021, he was named one of the top spreaders of misinformation about COVID-19 vaccines on social media. He was kicked off Instagram, along with his organization, Children's Health Defense, which was also removed from Facebook (Instagram reinstated Kennedy after he announced his presidential bid).

He told NPR that year that the social media bans had cost him "hundreds of thousands of dollars" in donations. But federal tax filings show otherwise: Children's Health Defense's revenue surged during the pandemic, from $3 million in 2019 to $7 million in 2020 to $16 million in 2021.

Today, Kennedy says the social media bans and the media's rejection of his views over the years are what galvanized him to run for president.

He accuses the White House of orchestrating his deplatforming. He is suing the Biden administration and media outlets including The Associated Press, The Washington Post, the BBC and Reuters for alleged censorship.

For Kennedy, his conviction that he's being censored is another example of the collusion between government agencies and corporations that he believes is the root of the United States' problems.

"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 on our country," he said in his April campaign announcement.

Claims of censorship have also become a core grievance of many conservatives and disaffected liberals, who see the rise of social media policies to combat harmful misinformation, conspiracy theories and election interference as infringing on their free speech rights.

From political scion to anti-vaccine crusader

Robert F. Kennedy Jr. is the son of the late U.S. attorney general, New York senator and Democratic presidential hopeful Robert F. Kennedy, as well as the nephew of former President John F. Kennedy. For years, he was best known as a wayward member of a famous, tragedy-stricken family and as a crusading environmental lawyer who helped clean up the Hudson River and launched a global movement to protect waterways.

It was his work fighting mercury pollution that led him into the world of vaccine skepticism. As he tells it, after hearing from mothers convinced their children had been harmed by a mercury-based preservative in routine vaccines, he became a convert to their cause. (The preservative in question was removed from most childhood vaccines in 2001 out of an abundance of caution and was never used in the measles, mumps and rubella vaccines that were the focal point for concerns about autism.)

In 2005, he made this argument in an exposé called "Deadly Immunity" in Rolling Stone and on Salon.com. The piece turned out to be deeply compromised by errors and selective use of evidence and was eventually retracted in 2011.

Despite study after study finding no connection between vaccines and autism, Kennedy has only dug in deeper to his discredited beliefs. For years, they put him on the fringe of American public discourse — until COVID-19.

How the pandemic united anti-vaccine and anti-government groups

The pandemic gave anti-vaccination activists new prominence and traction by offering easy answers to a public struggling to understand a fast-moving disease about which little was known.

"There was nothing else that happened in the world that could have globally made anti-vaccine ideology and content so mainstream," said Kolina Koltai, a researcher who studies the anti-vaccine movement. "The global pandemic made vaccines and disease the conversation."

The crisis also provided Kennedy, by then one of the most prominent figures in anti-vaccination circles, a broader set of targets in the form of changing public health guidelines, school and business shutdowns, and vaccine and mask mandates.

He wrote a book accusing Dr. Anthony Fauci, the nation's top infectious disease expert and formerly a White House adviser during the pandemic, of "help[ing] orchestrate and execute 2020's historic coup d'etat against Western democracy."

He compared vaccine mandates to Nazi Germany and promoted a film targeting disproven claims about vaccines to Black Americans. He touted the alternative treatments ivermectin and hydroxychloroquine, which have not been found to be effective at treating COVID-19. He appeared at the Christian nationalist ReAwaken America Tour alongside MAGA stars Roger Stone and Michael Flynn and QAnon conspiracy theorists.

"There was this coalescing of different groups that wouldn't really have crossed paths before the pandemic," said Aoife Gallagher, a research analyst at the nonprofit Institute for Strategic Dialogue, which studies extremism and disinformation. "What this allowed groups like Children's Health Defense and Robert F. Kennedy to do was to reach a much wider audience."

Kennedy's public trajectory echoed the increasing politicization of opposition to vaccines that emerged during the pandemic.

Dr. Paul Offit, director of the Vaccine Education Center at the Children's Hospital of Philadelphia and a longtime antagonist of Kennedy, says that before COVID-19, the anti-vaccine movement didn't map onto traditional political divides.

"When vaccines came along in December 2020, I thought people would just rush to get it and 100% of this population would be vaccinated and that the anti-vaccine movement would be neutered," he said. "Wrong."

Instead, Offit said, "this is the first virus in the history of humankind where you are more likely to die based on your political affiliation."

Why vaccine safety is often a rallying cry for anti-vaccine activists

While Kennedy is running as a Democrat, promising to "heal the divide" in American politics, many of his views are out of step with the mainstream. Americans of both parties resoundingly support childhood vaccines.

His extremely isolationist positions on immigration and foreign policy sound more like a candidate in the Republican primary. He says he would "seal the [U.S.-Mexico] border permanently" and blames the U.S. for Russia's invasion of Ukraine, saying Moscow acted in "good faith."

At his April campaign launch, Kennedy only obliquely nodded to his concerns about vaccines, instead referring to a "chronic disease epidemic" hurting Americans. He frequently tells interviewers that he's not anti-vaccine but instead an advocate for increased safety — while continuing to repeat disproven claims.

Vaccines go through extensive clinical trials, safety testing and monitoring in the United States. But the safety framing used by Kennedy and other vaccine skeptics makes their message "approachable," Koltai said. "They are ... degrading the trust and safety we have in institutional organizations like the CDC or the FDA and trying to manipulate data to make it seem like vaccines are less safe than they are," she said.

"Everyone wants safe vaccines. No one is saying we want less safe vaccines," she said. "They might frame this in a way that seems very appealing to everyone. But in reality, they're using the same sort of tropes and arguments and narratives that people in conspiratorial communities use."

Still, Kennedy's message has found fertile ground among an odd-bedfellows coalition of supporters, from vaccine opponents to far-right conspiracy theorists such as Jones, Stone and former Trump adviser Steve Bannon, to deep-pocketed Silicon Valley magnates including Musk, Twitter co-founder Jack Dorsey and venture capitalist David Sacks, who hold Kennedy up as a contrarian free-thinker.

"People have really embraced the idea of being anti-establishment over the past few years," Gallagher said. "That contrarian point of view of always going against whatever the mainstream is ... has become part and parcel of this wider conspiratorial world I think that a lot of people live in."

A podcast-centric presidential campaign

Kennedy's media strategy reflects his warm reception among an extremely online, right-leaning audience. He has turned up on a flurry of podcasts, from The Joe Rogan Experience to shows hosted by Peterson, former Fox News anchor Megyn Kelly, actor Russell Brand and venture capitalists Sacks, Jason Calacanis, Chamath Palihapitiya and David Friedberg.

The medium allows him to reach a big audience — Rogan's show, the country's most popular podcast, is estimated to draw as many as 11 million listeners per episode — and an audience that may not be tuning in to traditional news sources.

"I think the podcasts have the capacity this election for reaching people and allowing, you know, sort of dissident and insurgent candidates like myself to end-run the corporate media monoliths and to reach large numbers of Americans without going onto the networks," Kennedy told Peterson in an episode later removed from YouTube for containing vaccine misinformation.

In his lengthy podcast appearances, Kennedy is often given free rein to question the safety of vaccines and spout a host of other misleading or false claims — subjects that he avoided in his two-hour kickoff speech in April and that get no mention on his official campaign website.

Kennedy is a particularly well-suited podcast guest. Despite a medical condition that makes his voice hoarse and choked, once he gets going he can speak fluently and at length about any manner of subjects, from his legal victories to U.S. foreign policy history to colorful, emotional anecdotes of growing up in America's most storied political family.

"I think it makes total sense that this is the ecosystem that he has chosen," said Valerie Wirtschafter, a senior data analyst at the Brookings Institution who studies political podcasts. "Not only is it a space where you can really say whatever you want with very little repercussions or very little sort of pushback — it's also a space where people who are listening are inclined to believe anything that you say."

Kennedy's campaign has given him a platform that has long been denied him, with profiles in seemingly every media outlet. But he remains a long-shot candidate, and his campaign appears to be resonating more with Republicans than the Democrats who will vote in the primary.

Among Democrats, Kennedy's poll numbers range from 8% to 20%. To what degree that represents actual support versus affection for the Kennedy family name, appetite for a candidate who is not Biden and the very early stages of the presidential contest is up in the air.

What's not up for debate for scientists, researchers and public health officials is Kennedy's long track record of undermining science and spreading dubious claims.

"He has an enormous platform. He is going to, over the next many months, do a series of town hall meetings where he will continue to put bad information out there that will cause people to make bad decisions for themselves and their families, again putting children at risk and causing children to suffer," Offit said. "Because it's always the most vulnerable among us who suffer our ignorance."