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

Senators pressed Robert F. Kennedy Jr. on his past vaccine and abortion remarks in the first of two days of hearings before senators vote on whether to confirm him as President Trump’s health secretary.

If approved, Kennedy will control a $1.7 trillion agency that oversees food and hospital inspections, hundreds of health clinics, vaccine recommendations and health insurance for roughly half the country.