The White House on Thursday withdrew the nomination of Dr. Dave Weldon, a Republican and former member of Congress, to lead the Centers for Disease Control and Prevention just hours before he was to have appeared at a Senate confirmation hearing.

Reached by phone, Weldon said he learned of the decision Wednesday night and had been told by a White House official that “they didn’t have the votes to confirm” his nomination.

In a statement released later Thursday, Weldon, 71, blamed Sen. Susan Collins, R-Maine, a member of the Senate health committee, and Sen. Bill Cassidy, R-La., the committee’s chair, for torpedoing his nomination.

A spokesperson for Cassidy said the senator had been “looking forward” to the confirmation hearing. Collins’ office disputed Weldon’s account.

The withdrawal of Weldon’s nomination, which followed concerns raised during a meeting Tuesday with Republican Senate aides, is a significant setback for Robert F. Kennedy Jr., the new secretary of health and human services.

Weldon and Kennedy have known each other for 25 years, and both share a deep skepticism of the federal regulatory approach to vaccine safety.

Kennedy is also confronting a measles outbreak in West Texas, and has drawn criticism for promoting treatments like vitamin A and cod liver oil, and describing vaccination as a personal choice with unknown risks.

It was unclear if the White House had a backup candidate. The CDC is currently run by an acting director, Dr. Susan Monarez, who previously served as the deputy director of a newly formed biomedical research agency.

In an interview Thursday, Weldon said he had been excited by the prospect of serving his country again and helping to restore the public’s confidence in the CDC.

He said had also been looking forward to working with Kennedy on the MAHA, or Make America Healthy Again, agenda to curtail chronic diseases among Americans.

“It is a shock, but, you know, in some ways, it’s relief,” Weldon said. “Government jobs demand a lot of you, and if God doesn’t want me in it, I’m fine with that.”

Meetings Tuesday

The abrupt withdrawal appeared to stem from events that took place Tuesday, when Weldon met with Republican Senate staff members. In the statement, Weldon said aides to Collins were “suddenly very hostile” at the meeting, despite his “very pleasant” meeting with her two weeks earlier.

Weldon said Collins’ aides were “repeatedly accusing me of being anti-vax.” Collins’ office said that was untrue, and that aides had simply asked Weldon how he would respond to allegations that he opposed vaccination.

According to one person who attended the meeting, and spoke on condition of anonymity to share details, aides were concerned that Weldon seemed ill-prepared for the job and that he did not have a vision for the CDC.

On Wednesday, the day after the meeting, Kennedy had breakfast with Collins, Weldon said. He said Kennedy informed him that Collins had expressed reservations.

Weldon’s history

Weldon has repeatedly questioned the safety of the measles vaccine and criticized the CDC for not doing enough to prove that vaccines are safe.

“They never did it the right way,” he said in the statement. He also praised the work of discredited British doctor Andrew Wakefield, who wrongly proposed that vaccines cause autism.

“We might be able to do research and figure out why some kids have a bad reaction” to the measles-mumps-rubella vaccine, Weldon wrote, despite dozens of studies that have disproved a link. “Clearly, Big Pharma didn’t want me in the CDC investigating any of this.”

Weldon served in Congress for 14 years, from 1995 to 2009. During his tenure, he pushed to move the vaccine safety office away from CDC control, saying the agency had a conflict of interest because it also purchases and promotes vaccines.

Weldon is also a staunch opponent of abortion.

His signature legislative accomplishment was the Weldon Amendment, which bars health agencies from discriminating against hospitals or health insurance plans that choose not to provide or pay for abortions.

Like Kennedy, he had questioned the need to immunize children against hepatitis B, and argued that abstinence is the most effective way to curb sexually transmitted infections.