() Fired Centers for Disease Control and Prevention director Susan Monarez is expected to tell senators that she was fired for refusing to approve new vaccine recommendations without reviewing scientific evidence.

Sen. Bill Cassidy, R-La., opened the hearing by questioning the value of having Senate confirmation for a CDC director if that person could be fired less than a month later. He posed the question of whether senators missed something and bluntly stated the goal of the hearing is to find out what happened.

Sen. Bernie Sanders, I-Vt., said it was clear Monarez was fired for refusing to be a rubber-stamp for political views and called Health Secretary Robert F. Kennedy Jr.’s positions on vaccines dangerous. He defended the scientific evidence supporting the safety and efficacy of vaccines.

Monarez told senators that Kennedy gave her an ultimatum: “Preapprove” new vaccine recommendations from a controversial advisory CDC panel that Kennedy has stocked with some medical experts who doubt vaccine safety or be fired. That panel is expected to vote on new vaccine recommendations later this week.

Monarez, who was fired just weeks into her role, also said she was directed to fire senior CDC officials without cause.

“There is real risk that recommendations could be made restricting access to vaccines for children and others in need without rigorous scientific review,” she said.

Monarez referenced an upcoming meeting of the panel, which will discuss vaccines, including the COVID vaccine, Hepatitis B vaccine, measles, mumps and rubella (MMR) and chicken pox vaccine.

There was brief debate between Cassidy and Sanders at the start of the hearing, with Republicans seeking to swear in the witnesses and Democrats objecting. Sanders noted that Kennedy was not sworn in during his hearing nor have any other witnesses. He said it would be unfair to change the rules now.

Cassidy then noted it is illegal to lie to Congress anyway, prompting laughter in the chamber.

Kennedy has made significant changes regarding health policy, including appointing vaccine-skeptical personnel to key roles. Under his tenure, the Food and Drug Administration has also imposed new limits on the COVID-19 vaccine, though multiple medical groups have issued broader recommendations.

In recent days, Kennedy has faced pushback from both Democratic and Republican lawmakers over recommendations around vaccines.