Thursday on MSNBC’s “All In,” Sen. Peter Welch (D-VT) called Health Secretary Robert F. Kennedy a “lunatic,” declaring that he should be “fired.”

Discussing the Centers for Disease Control and Prevention director being fired, host Chris Hayes said, “Your reaction to what is happening at CDC right now?”

Welsh said, “Well, it’s horrifying I mean, there’s two things. One, very inspiring and the other very alarming. The inspiring part of this is the folks who resigned in solidarity with their director, who was standing up for science and for public health. The depressing part is that RFK is a lunatic. I mean, he is setting us back a century on public health. He basically does not believe that scientific basis for vaccines is valid.”

Hayes said, “Do you believe he should be fired and or resign?”

Welsh said, “He should be fired. He should resign and he never should have been appointed. And the fact is, by the way, he double crossed Senator Cassidy. You know, a lot of us didn’t believe it. We didn’t buy it but Senator Cassidy is a very respected colleague of Senator Murray and mine and all of us and a doctor. And he asked Kennedy on the vaccines, are you going to maintain the review system? Are you going to not set up a parallel system? Are you going to continue to respect science? And Kennedy gave him the answers that Cassidy was looking to hear. Cassidy believed him. But what you’re seeing with Secretary Kennedy right now is he’s totally and completely double crossing Senator Cassidy.”

Follow Pam Key on X @pamkeyNEN