Sen. Bill Cassidy, the top Republican on the Senate Committee on Health, Education, Labor and Pensions, concluded Thursday's hearing by saying he was "struggling" with the nomination due to Kennedy's vaccine positions. Kennedy notably refused to say vaccines don't cause autism as he faced pointed question from lawmakers.

Kennedy repeatedly refused to acknowledge scientific consensus that childhood vaccines don’t cause autism and that COVID-19 vaccines saved millions of lives

Kennedy has downplayed his history of advocating against vaccines since he was nominated to lead the Department of Health and Human Services.

Robert F. Kennedy Jr. was confronted with a number of his baseless claims and a vexing abortion issue. But Republican senators treaded lightly.

The health committee chairman, Sen. Bill Cassidy, R-La., also has expressed concerns about Kennedy's anti-vaccine work. A physician, Cassidy said earlier this month he “had a frank conversation” and “spoke about vaccines at length” with Kennedy. On Tuesday, Cassidy told reporters that he is still unsure if he is backing Trump’s nominee.

If confirmed by the Senate, Kennedy would head the Department of Health and Human Services (HHS), which oversees many of the country’s health agencies, from the Food and Drug Administration (FDA) to the Centers for Disease Control and Prevention (CDC).

RFK Jr. claimed he is not “anti-vaccine” and appeared unfamiliar with key aspects of healthcare insurance programs in his confirmation hearing.