Shortly after birth, newborns in the United States receive a few quick procedures: an Apgar test to check their vitals, a heel stick to probe for genetic disorders and various other conditions, and in most cases, a hepatitis B vaccine. Without that last one, kids are at risk of getting a brutal, and sometimes deadly, liver condition. Senator Bill Cassidy of Louisiana happens to know quite a lot about that. Before entering Congress in 2009, he was a physician who has said he was so affected by an 18-year-old patient with liver failure from the virus that he spearheaded a campaign that vaccinated 36,000 kids against hepatitis B.
Cassidy, a Republican, will now play a major role in determining the fate of Robert F. Kennedy Jr., Donald Trump’s pick for health secretary, whose confirmation hearings begin today on Capitol Hill. Kennedy has said that the hepatitis B vaccine is given to children only because the pharmaceutical company Merck colluded with the government to get the shot recommended for kids, after the drug’s target market (“prositutes and male homosexuals,” by Kennedy’s telling) weren’t interested in the shot. Kennedy will testify in front of the Senate Finance Committee, where Cassidy and 26 other senators will get the chance to grill him about his views. Though it might seem impossible for an anti-vaccine conspiracist to gain the support of a doctor who still touts the work he did vaccinating children, Cassidy has not indicated how he will vote. Similar to the Democratic senators who have come out forcefully against Kennedy, Cassidy, in an interview with Fox News earlier this month, said that RFK Jr. is “wrong” about vaccines. But he also said that he did agree with him on some things. (Cassidy’s office declined my request to interview the senator.)
That Kennedy even has a chance of winning confirmation is stunning in its own right. A longtime anti-vaxxer with a propensity for far-fetched conspiracy theories, RFK Jr. has insinuated that an attempt to assassinate members of Congress via anthrax-laced mail in 2001 may have been a “false flag” attack orchestrated by “someone in our government” to gin up interest in the government preparing for potential biological weapon threats. He has claimed that COVID was “targeted to attack Caucasians and Black people,” and that 5G is being used to “harvest our data and control our behavior.” He has suggested that the use of antidepressants might be linked to mass shootings. Each one of these theories is demonstrably false. The Republican Party has often found itself at war with mainstream science in recent years, but confirming RFK Jr. would be a remarkable anti-science advance. If Republican senators are willing to do so, is there any scientific belief they would place above the wishes of Donald Trump?
A number of Republicans have already signaled where they stand. In the lead-up to the confirmation hearings, some GOP senators have sought to sanewash RFK Jr., implying that his views really aren’t that extreme. They have reason to like some of what he’s selling: After the pandemic, many Republicans have grown so skeptical of the public-health establishment that Kennedy’s desire to blow it up can seem enticing. And parts of RFK Jr.’s “Make America Healthy Again” agenda do in fact adhere to sound scientific evidence. His views on how to tackle America’s epidemic of diet-related diseases are fairly well reasoned: Cassidy has said that he agrees with RFK Jr.’s desire to take action against ultra-processed foods. Kennedy appears to have won over the two other Republican doctors on the committee, Senators Roger Marshall of Kansas and John Barrasso of Wyoming. Marshall has been so enthusiastic about Kennedy’s focus on diet-related diseases that he has created a “Make America Healthy Again” caucus in the Senate. Although Barrasso hasn’t formally made an endorsement, he has said that Kennedy would provide a “fresh set of eyes” at the Food and Drug Administration. (Spokespeople for Barrasso and Marshall did not respond to requests for comment.)
[Read: Everyone agrees Americans aren’t healthy]
Meanwhile, Kennedy appears to have gone to great lengths to sand down his extremist views and present himself as a more palatable candidate. “He told me he is not anti-vaccine. He is pro–vaccine safety, which strikes me as a rational position to take,” Senator John Cornyn of Texas told Politico. He has also done more to drum up unnecessary fear about COVID shots than perhaps anyone else in the country. Nearly four years ago, Kennedy petitioned the federal government to revoke authorization for the shots, because “the current risks of serious adverse events or deaths outweigh the benefits.” (COVID shots are highly safe and effective. A spokesperson for Kennedy did not respond to a request for comment.)
Especially on the right, Kennedy’s conspiracy theories have not consumed his candidacy: With concerns about conflicts of interest, his support of abortion, and generally strange behavior (such as dumping a dead bear in Central Park), there is much to debate. If Republican senators skirt around his falsehoods during today’s confirmation hearings, it will be evidence of their prevailing capitulation to Trump. And it also may be a function of Kennedy’s rhetorical sleights. As Benjamin Mazer recently wrote in The Atlantic, Kennedy is not simply a conspiracy theorist, but an excellent one. He’s capable of rattling off vaccine studies with the fluency of a virologist, which boosts his credibility, even though he’s freely misrepresenting reality.
[Read: RFK Jr. is an excellent conspiracy theorist]
During his recent appearance on Joe Rogan’s podcast, Kennedy claimed that thimerosal, a preservative containing mercury used to protect vaccines from contamination, was found to cause “severe inflammation” in the brain of monkeys. Kennedy was able to quickly name the lead author and introduce the methods as if he has read the study hundreds of times. But Kennedy’s central claim—that the brains of monkeys given thimerosal were severely inflamed—is a “total misrepresentation” of the study, its lead author, Thomas M. Burbacher, told me. The problem is that Kennedy gets away with these claims because very few listeners are going to log onto PubMed to track down the study Kennedy is referencing, let alone read through the entire thing.
In theory, senators should be equipped to push back on his schtick. RFK Jr.’s positions are hardly a mystery, and senators have advisers to help them prepare for such hearings. Regardless of Kennedy’s pseudoscientific beliefs, some Republicans may support him simply because they are wary of bucking their president. Before Kennedy even makes it to a full vote from the Senate, he has to receive approval from the Senate Finance Committee: Given the tight margins in the committee, Kennedy can’t afford to lose a single vote from Republicans sitting on that panel, assuming that no Democrats support his nomination. I reached out to the offices of seven Republican senators on the committee who haven’t already backed Kennedy for clarity on where they stand; none of them gave me a straight answer on how they’d vote.
In all likelihood, the first big decision in Kennedy’s nomination will fall to Cassidy. He has proved willing to oppose Trump before. Cassidy was one of seven Republicans who voted to convict Trump during his second impeachment proceedings. That led Louisiana’s Republican Party to formally censure him, and has drawn him a primary challenger for his 2026 reelection bid. Although Cassidy criticized Trump during the 2024 campaign, he now seems eager to support him. “Today, the American people start winning again,” Cassidy wrote in a statement on Inauguration Day.
Perhaps Cassidy will still dissect Kennedy’s views with the precision of a surgeon’s scalpel. He likes to dive deep into health-care minutiae any chance he gets. (I would know: He once pulled out his iPad and lectured me and other reporters about some arcane drug-pricing policy.) But if today’s meeting is full of softball questions, it could put RFK Jr. on his way to confirmation. That would send a message that, science-wise, the Senate is willing to cede all ground. Trump could pursue the most radical parts of the Project 2025 agenda, such as splitting up the CDC, or Kennedy could launch a full-blown assault on vaccines—and the Senate would be in a much less powerful position to stop it even if it wanted to. If senators hand the keys of a nearly $2 trillion health-care agency to a known conspiracy theorist, anything goes.