Robert F. Kennedy Jr. 's bid to be the nation's top health official is uncertain after a key Republican joined Democrats to raise persistent concerns over the nominee's deep skepticism of routine childhood vaccinations that prevent deadly diseases.

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.

Robert F. Kennedy Jr. said he wasn’t antivaccine as senators pressed on his past remarks, in the first of two days of hearings over his nomination for health secretary.

Robert F. Kennedy Jr. faced aggressive questions about his skepticism of vaccines and other issues during the first of two scheduled Senate confirmation hearings.

The longtime liberal faces deep skepticism over his public health views. “Frankly, you frighten people,” one Democratic senator told his former roommate.

Watch live as RFK Jr. faces questions from senators in his confirmation hearing as President Trump’s nominee to lead the Department of Health and Human Services.

Kennedy also said gender-affirming care for children has "catastrophic" impacts and that children are not equipped to make judgments about receiving such care. He said he would re