Sen. Bill Cassidy is finding himself in a political quandary after Health and Human Services Secretary Robert F. Kennedy Jr. this week replaced all members of an advisory board on immunizations.

The Louisiana Republican, also a medical doctor, had hesitated earlier this year as chair of the Senate Health, Education, Labor and Pensions (HELP) Committee over confirming Kennedy, but said that he had secured promises from him not to hinder the public's confidence in vaccines, reports The Hill.

He also promised in February, after voting to advance the nomination, to "rebuff any attempts to remove the public's access to lifesaving vaccines without ironclad, causational scientific evidence that can be defended before the mainstream scientific community and before Congress."

Cassidy also said that Kennedy pledged to maintain the Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices (ACIP) without making changes.

But on Monday, Kennedy fired all 17 members of the panel, later naming 8 new members, including a strong critic of the COVID-19 vaccines.

Cassidy has not publicly confronted Kennedy over the announcement, potentially because of his upcoming reelection bid.

The senator already has a strike against him among Republicans for voting to convict President Donald Trump of impeachment in connection with the Jan. 6 protests.

After that, state Republicans changed election rules to change the primary to a closed election, allowing only Republicans and people who aren't registered to any party to vote.

But Cassidy has also supported all of Trump's Cabinet picks and raised $1.36 million during the first quarter of 2025 and has $7.5 million cash on hand, the most by any incumbent Louisiana senator at this stage of a reelection campaign.

However, Trump and Louisiana Gov. Jeff Landry have discussed having his endorsement in the key race to go to Rep. Julia Letlow rather than Cassidy, reports The Hill.

State Treasurer John Fleming is also running in the GOP primary against Cassidy.

Cassidy has not said much about Kennedy's advisory board move or if the secretary violated their agreement.

He did comment on X that "the fear is that the ACIP will be filled up with people who know nothing about vaccines except suspicion. I've just spoken with Secretary Kennedy, and I'll continue to talk with him to ensure this is not the case."

Kennedy has taken other steps on vaccines, including stating that pregnant women and healthy children do not need COVID-19 shots, and canceling mRNA vaccine contracts.

He also pushed out the head of the Food and Drug Administration's vaccine division, and refused to testify upon request in April, going against an agreement he'd reached with Cassidy to speak every quarter upon request.

Kennedy did testify to the HELP Committee for his HHS appropriations request, with Cassidy pointing out that his testimony was the first from an HHS secretary in at least 20 years.

Cassidy did not speak on vaccines during the hearing, but Democrats did, including Sen. Chris Murphy, D-Conn., who accused the secretary of lying about supporting vaccines.

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