Kyra Kennedy, 29, is the youngest daughter of health secretary nominee Robert F. Kennedy Jr.

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

Kathleen "Kick" Kennedy is the eldest daughter of Robert F. Kennedy Jr., who could be confirmed as health secretary in Trump's administration.

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.

Caroline Kennedy, a former US ambassador and daughter of John F. Kennedy, claimed her cousin, Robert F. Kennedy Jr., was "unqualified" for HHS Secretary and a "predator." View Entire Post ›

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.

Caroline Kennedy said in a scathing letter about her cousin, Robert F. Kennedy Jr., that she felt "an obligation to speak out."

Watch: RFK's cousin Caroline Kennedy urges Senate against confirming 'predator' for US Health Secretary Caroline Kennedy - the cousin of Robert F Kennedy Jr - has urged US senators to reject her cousin as America's next health and human services secretary in a scathing letter released on Tuesday.