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

Robert F. Kennedy Jr. has said vaccines are not safe. His support for abortion access has made conservatives uncomfortable. And farmers across the Midwest are nervous over his talk of banning corn syrup and pesticides from America's food supply.

The hearings were packed to capacity with protesters and fans, while the spillover crowd hung out in hallways and overflow rooms.