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.

Caroline Kennedy, daughter of former President John F. Kennedy, warned senators of her “predator” cousin ahead of his first confirmation hearing on Wednesday. In a letter first reported by The Washington Post, she wrote that his victims included family members and parents of sick children.

Robert F. Kennedy Jr. will face the Senate for two days of confirmation hearings in a bid become the leader of Health and Human Services.

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.

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

Caroline Kennedy has released a scathing letter describing her cousin Robert F Kennedy as a cruel, unqualified and dangerous.

The former U.S. ambasador — the last surviving child of Jacqueline and John F. Kennedy — urged lawmakers to reject RFK Jr.’s nomination as health secretary.

The former ambassador called Robert F. Kennedy Jr. "unqualified" and said his views on vaccines are "dangerous and willfully misinformed."

Caroline Kennedy, a member of the famed U.S. political family, urged senators on Tuesday to reject her cousin Robert F. Kennedy Jr.'s nomination to lead the top U.S. health agency, calling him a "predator" and his healthcare views "dangerous.