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."

The daughter of former President John F Kennedy, Caroline Kennedy said that Robert F Kennedy Jr, known as RFK Jr, has discouraged vaccinations for his own profit. She added he does not have the medical, financial or government experience to lead the Department of Health and Human Services. Republican President Donald Trump nominated him in November.

A spokesperson for RFK Jr did not immediately respond to a request for comment.

Senators will question RFK Jr on Wednesday starting at 10 a.m. about his views before they vote on whether to confirm his nomination.

The Washington Post first reported the letter.

RFK Jr has long sown doubts about the safety and efficacy of vaccines that have helped curb disease and prevent deaths for decades. He disputes the anti-vaccine characterization and has said he would not prevent Americans from getting inoculations.

"Bobby has gone on to misrepresent, lie and cheat his way through life today," Caroline Kennedy said in a video on social media platform X, in which she read her letter addressed to senators.

U.S. doctors, nurses, researchers, scientists and caregivers "deserve a secretary committed to advancing cutting-edge medicine, to save lives, not to rejecting the advances we have already made," said Caroline Kennedy, a former ambassador to Australia and Japan who served during the Democratic Biden and Obama administrations. "They deserve a stable, moral and ethical person at the helm of this crucial agency."

In written testimony for the Finance committee, RFK Jr said he is not "anti-vaccine" or "anti-industry" and that he believes "vaccines have a critical role in healthcare," pointing to his own children being vaccinated, according to the document seen by Reuters.

However, he has led the anti-vaccine group Children's Health Defense and in a 2023 interview with podcaster Lex Fridman said no vaccines are safe and effective.

RFK Jr has said he wants to work to end chronic disease, break any ties between employees at the U.S. drug regulator and industry and advise U.S. water systems to remove fluoride.

RFK Jr has faced new scrutiny over his ties to Wisner Baum, a law firm specializing in pharmaceutical drug injury cases.

He has an arrangement to earn 10% of fees awarded in contingency cases he refers to the firm, according to a letter RFK Jr wrote to an HHS ethics official released last week.

If confirmed, RFK Jr would retain that financial interest in cases that do not directly impact the U.S. government, the letter said.