The man who hopes to be President Trump's Health secretary says he needs to see data showing vaccines are safe, but dismissed evidence shown by a Republican senator.

Robert F. Kennedy Jr.’s nomination 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.

Kennedy’s bid to serve as America’s top health official may be decided by a handful of Republicans, including several senators who questioned him Thursday.

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.

As Robert F. Kennedy Jr. faced skeptical senators Thursday in the second day of his confirmation hearing to lead the department of Health and Human Services, Sen. Bill Cassidy confronted Kennedy about vaccines.

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

Kennedy Jr. faced a plethora of tough questions on vaccines, abortion and public health policy during his Senate confirmation hearing Wednesday as President Donald Trump’s pick for secretary of Health and Human Services (HHS).