WASHINGTON — After the confirmation of President Obama’s choice to run the Centers for Medicare and Medicaid Services (CMS) was held up for nearly three months by Republicans, the president bypassed the legislators earlier this month and appointed Donald Berwick to the post while the Senate was on its summer recess.

Obama had nominated Berwick in April to run the federal medical programs, but his Senate confirmation was held up by Republicans who expressed worries that he would ration health care as a way to cut costs.

Berwick, a professor of pediatrics and public health at Harvard, also served as head of the Institute for Healthcare Improvement, a nonprofit organization that works to improve global health care.

The president can fill top federal vacancies that would normally require Senate approval while the Senate is in recess. Many presidents have used this power to get around Senate objections.

“It’s unfortunate that at a time when our nation is facing enormous challenges, many in Congress have decided to delay critical nominations for political purposes,” Obama commented. “These recess appointments will allow three extremely qualified candidates to get to work on behalf of the American people right away.”

Berwick’s appointment as CMS administrator places him at the heart of the administration’s overhaul of the nation’s health care system. White House communications director Dan Pfeiffer said in a statement the day the appointment was made that the job of CMS administrator was too important to leave unfilled.

Meanwhile, Senate Republicans did not let up on their criticism of Berwick.

Minority leader Mitch McConnell (R., Ky.) accused the Obama administration of arrogantly circumventing the American people by appointing “one of the most prominent advocates of rationed health care to implement their national [health care] plan.”