For the first time in modern American history, a skeptic of medical research could be responsible for safeguarding public health.

Like Trump, Kennedy for years has wielded a firehose of falsehoods across multiple fronts and has engaged in assorted misconduct and odd behavior, so much so that the individual lies and misdeeds zip by and blur into a mess that becomes tough for the media to thoroughly depict and hard for the public to absorb.

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.

Robert F. Kennedy Jr. was confronted with a number of his baseless claims and a vexing abortion issue. But Republican senators treaded lightly.

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.

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