Sen. Bill Cassidy helped clinch Robert F. Kennedy Jr.’s bid to lead the Department of Health and Human Services months ago after securing commitments from Kennedy to, among other things, avoid undercutting public faith in vaccinations. Now, the Louisiana Republican says the secretary has “lived up to” those promises — even as critics accuse Kennedy of trying to poison the well of faith in vaccines.
Ahead of Kennedy’s Wednesday testimony in front of the Senate committee Cassidy chairs, the senator told NBC News that he has a “good working relationship” with Kennedy. And asked whether the secretary has lived up to his commitment not to sow distrust in vaccines, Cassidy replied: “All I’ll say about the commitment is, so far, he’s lived up to them.”
Later in the hearing, Kennedy, the former chair of an anti-vaccine group that has long spread unfounded claims about immunizations, sparred with Sen. Chris Murphy, D-Conn., over vaccines. Murphy accused Kennedy of deciding to “repeatedly undermine the [measles] vaccine with information that is contested by public health experts,” adding that “if I were the chairman, [Cassidy], who believes in vaccines and voted for you because he believed what you said about supporting vaccines, my head would be exploding.”
“If I advised you to swim in a lake that I knew there to be alligators in, wouldn’t you want me to tell you there were alligators in there?” Kennedy said in response to Murphy's criticisms.
The episode, and Murphy’s repeated decision to invoke Kennedy’s promises to Cassidy to argue he misled the committee about his stance on vaccines, highlights the tenuous truce Cassidy has carved out with Kennedy, particularly as the Louisiana senator faces the prospect of a primary challenge from his right flank in 2026. He has long been on tenuous political ground with Trump's MAGA movement, after voting to convict the president on impeachment charges following the Jan. 6, 2021, Capitol riot.
While Cassidy largely avoided the issue of vaccines and Kennedy's record during Wednesday's hearing, he did briefly step in "for the record" to note that Kennedy erred by saying that no vaccine besides the Covid shot had been tested against a placebo.
Cassidy, a medical doctor, publicly wavered over whether to support Kennedy's confirmation and spent much of Kennedy's confirmation hearing peppering him with questions about his record on vaccines. Upon announcing his support for Kennedy's nomination, Cassidy said Kennedy had made a series of promises to him, largely about protecting government work and public faith in vaccines.
Yet Kennedy has added to his record of vaccine-related controversies in his short tenure leading HHS. He falsely claimed during a CBS News interview last month that the measles vaccine’s protection “wanes very quickly“ and that many vaccines on the market aren’t “safety tested” amid the recent outbreak of the virus. Those comments drew immediate rebukes from top public health officials.
HHS is embarking on a series of studies to investigate autism rates in children, a move that comes after Kennedy has spent much of his career questioning whether vaccines are to blame for the disorder, although decades of research have found no evidence of a link between vaccines and autism. It’s unclear whether the study will look into those claims or not.
Meanwhile, widespread cuts across the federal government included more than $2 billion in cuts from grants to increase access to childhood vaccines for those who can’t afford them.
Cassidy asked during Wednesday’s hearing for assurances that various cuts across the federal government wouldn't hurt Americans and the nation's public health system.
He predicted that Kennedy would provide “clarity” with his testimony, helping him “gain the trust of the American people, putting their minds at ease.”
“People fear change even when it’s from worse to better, but without a clearly defined plan or objective, people assume the worst. Much of the conversation about HHS’s agenda has been set by anonymous sources in the media and individuals with a bias toward the president,” he said.
“Americans need direct reassurance from the president and from you, Mr. Secretary, that these reforms will make their lives easier, not harder. And that’s why I’ve invited you: No one can make that case better than you,” Cassidy added. (Among the conditions Cassidy set forth when he said he'd vote to confirm Kennedy was that he would testify to Congress "on a quarterly basis, if requested.")
Vaccines weren't a major topic of conversation at the hearing until Murphy, the Connecticut Democrat, began to speak. He quickly accused Kennedy of not telling the truth to the committee and not following through on his promises to the Republican chairman, adding that Kennedy "constantly questioning the efficacy or safety of the vaccine results in less people getting the vaccine."
Kennedy replied by saying he promised the committee "radical transparency" and that he's "not going to tell people everything is safe and effective if I know that there's issues." Later, he answered a question from New Hampshire Democratic Sen. Maggie Hassan by saying, "the best way to stop the spread of measles is vaccination."
Cassidy's support for Kennedy, which delivered the Trump administration a key early win as he assembled his Cabinet, comes as the Louisiana Republican is gearing up for a tough political fight and has faced criticism from the more conservative wing of the party.
State Treasurer John Fleming, who is running for Cassidy's seat in 2026, has criticized Cassidy for voting to convict Trump in the Senate following the House's 2021 move to impeach him. The Louisiana state GOP censured Cassidy for the vote at the time.
But Cassidy's political operation has signaled that it's gearing up for a tough race — it touted his first-quarter fundraising, which left him with a multimillion dollar cash-on-hand advantage over Fleming after the first quarter of 2025.
And his campaign released portions of an internal poll showing Cassidy well ahead of Fleming, although his favorability rating among likely Republican voters was below 50%.
