Senators alarmed by chaos at the Centers for Disease Control and Prevention grilled Health Secretary Robert F. Kennedy Jr. over what some are calling his politicization of vaccine policy and his past promises not to interfere in scientific decisions.

Kennedy, a longtime vaccine skeptic who has promoted misinformation about public health, recently ousted his hand-picked CDC director, Dr. Susan Monarez, with President Donald Trump's backing in a blowup that saw several top officials quit the agency.

“He absolutely must go,” Sen. Angela Alsobrooks, D-Maryland, said at a rally before the hearing. “The American people do not deserve to have their health endangered by an HHS secretary who thinks he knows better than experts.”

More: Is Trump a supporter of COVID-19 vaccines? That depends on when you ask.

The September 4 hearing before the Senate Finance Committee comes as Kennedy’s Make America Healthy Again commission delivered an action plan to the White House to combat chronic diseases in U.S. children. That plan has yet to be released to the public.