Robert F. Kennedy Jr., a former presidential candidate and environmental activist, endorsed Donald Trump last year and threw his weight behind a campaign to “Make America Healthy Again.” For the past two decades he has been best known for airing skeptical views on vaccines.

As he seeks to lead the health department, Mr. Kennedy wore a thin tie dotted with feathered creatures to cap a classic suit.

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.

What to know from Robert F. Kennedy, Jr.’s hearings before the Senate Finance Committee on Wednesday and the Senate Health, Education, Labor, and Pensions on Thursday.