The man who hopes to be President Donald Trump's health secretary said he needed to see data showing vaccines are safe, but when an influential Republican senator did so, he dismissed it.

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.

The public dispute between Robert F. Kennedy Jr. and Caroline Kennedy has the political family back in the spotlight. Meet key members of the Kennedy family.