Kennedy is up against concerned senators on both sides of the aisle who are seeking clarity and reassurances about his qualifications, advocacy against vaccines, promotion of public health conspiracies, and an array of financial conflicts of interest from past roles.

The HHS nominee will field questions from two Senate panels: the Finance Committee on Wednesday and the Health, Education, Labor, and Pensions Committee on Thursday.

“He’s got to have a good hearing [and] address some of the concerns we all know like vaccines,” said Sen. Thom Tillis (R-NC), who is up for reelection and proved key to confirming Defense Secretary Pete Hegseth last week. “He has the distinction to have to convince two committees.”

Leading up to his first hearing, Kennedy faced new blistering criticism from a family member: Caroline Kennedy, a cousin to the HHS nominee and former ambassador to Australia under President Joe Biden.

Caroline Kennedy, in a letter to top senators on the committees that will conduct Kennedy Jr.’s confirmation hearings, assailed him as an attention-seeking “predator” who is “unqualified” to lead HHS.

“He lacks any relevant government, financial, management, or medical experience. His views on vaccines are dangerous and willfully misinformed,” Caroline Kennedy wrote. “These facts alone should be disqualifying. But he has personal qualities related to this position which, for me, pose even greater concern.”

In what she described as a “perverse scene of despair and violence,” Caroline Kennedy went on to recall how her cousin would “put baby chickens and mice in the blender to feed his hawks” as an example of his broader character and disposition.

But more vital than the latest criticism from another member of the extensive Kennedy family tree and his fraught standing with Democrats will be his ability to woo on-the-fence Republicans. Kennedy Jr. must advance both committees before a floor vote, where he can afford no more than three rebellions in the GOP’s 53-47 majority if all Democrats oppose him.

“I’m a data-driven person,” said Tillis, who sits on the Senate Finance Committee and expressed concerns about Kennedy Jr.’s anti-vaccine views. “All these [nominees] that are making scientific conclusions about certain things need to be backed up with scientific data, and I’m assuming he’ll be prepared to discuss that.”

Centrist Sens. Susan Collins (R-ME) and Lisa Murkowski (R-AK), both of whom voted against Hegseth, sit on the Senate HELP Committee. Sen. Bill Cassidy (R-LA), another wild card in Kennedy Jr.’s confirmation, chairs the Senate Finance Committee and is also a member of the HELP Committee.

Cassidy, who already faces a primary challenger for reelection, declined to discuss Kennedy Jr. ahead of the hearings. He referred reporters who peppered him with questions to committee staff.

In a statement to the Washington Examiner, a Cassidy spokesperson would only go so far as to say, “Chairman Cassidy is looking forward to the hearings this week.”

Kennedy Jr. faces broad opposition from Democrats, particularly those who sit on the two panels that will have the opportunity to grill the nominee.

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Senate Minority Leader Chuck Schumer (D-NY) said he was personally unable to “recall a nominee more dangerous to the health of Americans than Mr. Kennedy.”

“He will pretend as if he’s now found religion on vaccines, or that his words have been twisted unfairly, or that he never intended to say he is anti-vaccines,” Schumer predicted. “Nobody should believe Mr. Kennedy’s 11th-hour conversion on vaccines.”