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.

Aside from Cassidy, Republicans on the health committee remained friendly to Kennedy. Republican Sen. Tommy Tuberville of Alabama, who said his two sons wanted to vote for Kennedy in the presidential election, told the hearing that his granddaughter, due in the coming weeks, would not “be a pincushion” when it came to vaccines.