In one of his first acts as administrator, Berwick will be in Washington on Tuesday morning to help unveil final health information technology regulations.
The move by Obama to skirt the confirmation process angered Republicans and some Democrats who are seen as pivotal in vetting administration picks.
“This appointment had everything to do with the administration's fear of letting Americans hear (Berwick's) well-known views about government-run care and about how he plans to implement the president's plan to cut a half-trillion dollars from Medicare while limiting the choices seniors now enjoy,” Senate Minority Leader Mitch McConnell (R-Ky.) said during a speech on the Senate floor.
Republicans Jon Kyl of Arizona and John Barrasso of Wyoming also knocked Obama's use of what's known as a “recess appointment.”
Democrats Richard Durbin of Illinois and Sheldon Whitehouse of Rhode Island defended the choice of Berwick.
Whitehouse said that the president's signature on the 4-month-old health reform law was only the beginning, and that the measures would not go far if they were not applied “both vigorously and wisely.”
“Don Berwick is simply, hands down, the best person to do that,” he added.