Dave Weldon will likely be questioned about a measles infections, a plan to study a debunked link between vaccines and autism, and the ongoing bird flu outbreak.

Dr. David Weldon had been out of the national spotlight for more than 15 years when he was nominated to head the Centers for Disease Control and Prevention. But many anti-vaccine advocates knew him well.

A person familiar with the matter said the White House pulled the nomination because it became clear Weldon did not have the votes for confirmation.