Robert F. Kennedy Jr.'s record of questioning childhood vaccine safety came under fire from a key Republican at the Trump HHS pick's confirmation hearing.

While Mr. Kennedy, seeking the job of health secretary, has been vocal about vaccines and his desire to overhaul the nation’s diet, he has said very little about other issues.

If confirmed by the Senate, Kennedy would head the Department of Health and Human Services (HHS), which oversees many of the country’s health agencies, from the Food and Drug Administration (FDA) to the Centers for Disease Control and Prevention (CDC).

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

Robert F. Kennedy Jr. is appearing before the Senate Committee on Finance on Wednesday as he seeks confirmation to lead the Department of Health and Human Services.

RFK Jr. claimed he is not “anti-vaccine” and appeared unfamiliar with key aspects of healthcare insurance programs in his confirmation hearing.

The health committee chairman, Sen. Bill Cassidy, R-La., also has expressed concerns about Kennedy's anti-vaccine work. A physician, Cassidy said earlier this month he “had a frank conversation” and “spoke about vaccines at length” with Kennedy. On Tuesday, Cassidy told reporters that he is still unsure if he is backing Trump’s nominee.