Dr. Dave Weldon was to have appeared on Thursday in a confirmation hearing before the Senate health committee. He has close ties to Robert F. Kennedy Jr., the new health secretary.

Weldon was told Wednesday night that his nomination was being withdrawn, another Trump administration official said. The White House decided to pull Weldon’s nomination when it became clear that he would not have the votes to be favorably reported out of committee because of his past controversial comments about vaccines, the official said.