The White House on Thursday withdrew the nomination of Dr. Dave Weldon, a Republican and former congressman, 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, Dr. Weldon said he had learned of the decision on 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 on Thursday, Dr. Weldon, 71, blamed Senator Susan Collins, Republican of Maine and a member of the Senate health committee, and Senator Bill Cassidy, Republican of Louisiana and the committee’s chairman, for torpedoing his nomination.
A spokesman for Mr. Cassidy said the senator had been “looking forward” to the confirmation hearing. Ms. Collins’s office disputed Dr. Weldon’s account.
“I did not express concerns to the White House. I had some reservations, but I certainly had not reached a final judgment,” Ms. Collins said Thursday.
The withdrawal of Dr. Weldon’s nomination, which followed concerns raised during a meeting on Tuesday with Republican Senate aides, is a significant setback for Robert F. Kennedy Jr., the new secretary of health and human services.
Dr. Weldon and Mr. Kennedy have known each other for 25 years, and both share a deep skepticism of the federal regulatory approach to vaccine safety.
Mr. 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.
The decision to withdraw the nomination was first reported by Axios.
It was unclear if the White House had a backup candidate. The C.D.C. 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 on Thursday, Dr. Weldon said he had been excited by the prospect of serving his country again and helping to restore the public’s confidence in the C.D.C.
He said had also been looking forward to working with Mr. 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,” Dr. Weldon said. “Government jobs demand a lot of you, and if God doesn’t want me in it, I’m fine with that.”