Bill Cassidy

On CBS, Cassidy accused Kennedy of breaking an agreement to make it clear on Centers for Disease Control and Prevention materials that there was no scientific foundation for claims that vaccines cause autism.

“Once you lose trust in somebody, you’re not quite sure what to trust going forward. In fact, you don’t trust anything,” Cassidy said. “If you build public health upon a foundation of lies, then you’re going to have the absence of adequate public health. You need to build everything in life on truth.”

He argued that he negotiated his support for Kennedy ahead of his confirmation to ensure that he would be able to enact guardrails over Kennedy’s policies.

“Either he was going to be in a position where there were guardrails ... or he was going to be appointed White House health czar, in which case he would have the president’s ear without the guardrails,” Cassidy told CBS. “You can criticize it, but I chose to have the one with the guardrails.”

Last month, Cassidy lost his primary race in Louisiana, meaning he will end his 11-year career in the Senate in January. The senator, who voted to convict Trump in his impeachment trial after the January 6, 2021, insurrection at the U.S. Capitol, lost to a Trump-endorsed candidate.

Cassidy’s tensions with Trump flared anew on Capitol Hill last week.

The two got into what Cassidy described as a shouting match during Trump’s visit to a Senate lunch as the senator confronted the president over the Iran war.

“I lost my temper,” Cassidy told reporters after the lunch. “That’s inappropriate. It’s the Irish in me - but I, again, matched his tone and volume.”

While Cassidy initially supported a measure that would have reined in Trump’s powers in Iran, he switched sides after receiving a briefing on the war from Trump’s special envoy to the Middle East, Steve Witkoff. The measure failed.

Cassidy told CBS that he believes Trump treats Congress like an “appendage” on Iran, and that he wants better communication.

“Congress wants to be read in, and Congress has our rules and procedures that our Founding Fathers set up, and they set it up precisely so that there would not be too powerful of an institution of a presidency designed to reflect all of the American people, not just the will of one person,” he said.