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.

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.

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

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., Trump’s controversial pick to lead Health and Human Services, testified before a Senate panel that is crucial to advance his nomination.