Bill Cassidy

Sen. Bill Cassidy, R-La., faces a looming primary challenge on Saturday as Louisiana’s newly energized “Make America Healthy Again” movement targets the physician-turned-lawmaker over his support for vaccines and clashes with Health and Human Services Secretary Robert F. Kennedy Jr.

Cassidy, a two-term incumbent seeking re-election in Louisiana’s first closed-party Senate primary in decades, is battling Rep. Julia Letlow, R-La., who has President Donald Trump’s endorsement, and state Treasurer John Fleming in a race that has become a national test of the MAHA movement’s political influence ahead of the 2026 midterm elections.

The Louisiana contest has also drawn outsized national attention because Cassidy was one of seven Republican senators who voted to convict Trump after the Jan. 6, 2021 Capitol breach, a vote that led the Louisiana Republican Party to censure him and made him a long-term target among Trump loyalists.

Trump intensified the intraparty battle in January when he endorsed Letlow before she formally entered the race, calling on the congresswoman to challenge Cassidy.

The tensions escalated further this month after Trump withdrew wellness influencer Casey Means as his nominee for surgeon general and publicly blamed Cassidy for helping block the nomination.

“I nominated Casey, a strong MAHA Warrior, at the recommendation of Secretary Kennedy, who understands the MAHA Movement better than anyone, with perhaps the possible exception of ME!” Trump wrote on social media. “Nevertheless, despite Senator Cassidy’s intransigence and political games, Casey will continue to fight for MAHA on the many important Health issues facing our Country.”

Kennedy also attacked Cassidy in a post on social media, writing: “Bill Cassidy once again did the dirty work for entrenched interests seeking to stall the MAHA movement and protect the very status quo that has made America the sickest nation on earth.”

Cassidy rejected the criticism and told reporters the White House had “known for a while [Means] didn’t have the votes to pass.”

After Trump later called Cassidy “a very disloyal person,” the senator responded: “I’m loyal to the United States of America.”

The race has evolved into a proxy fight between establishment Republicans and the populist health movement aligned with Kennedy, whose supporters have increasingly targeted lawmakers seen as obstacles to his agenda.

Cassidy, a liver specialist who chairs the Senate Health, Education, Labor and Pensions Committee, has repeatedly defended vaccines and publicly challenged Kennedy’s views on vaccine safety, even while ultimately voting to confirm him as HHS secretary after securing commitments on public health policy.

Political analysts say Louisiana’s new election system could further complicate Cassidy’s path to re-election.

The state abandoned its longtime open “jungle primary” format in 2024 and shifted to closed partisan primaries for federal races, limiting participation to registered Republicans and unaffiliated voters in the GOP contest.

Polls and Republican operatives have suggested the race could head to a June runoff if no candidate wins a majority Saturday.

Despite the attacks, Cassidy has defended his conservative record and pointed to his work securing federal funding for Louisiana projects while emphasizing his independence from Trump.