A Massachussetts pediatrician and Harvard University professor who will oversee Medicare and Medicaid is expected to be appointed by President Obama, sources informed.

An official however added that the nomination of Donald Berwick has not been made yet.

One of the nation's leading authorities on health care quality and improvement, Berwick, is the president and chief executive officer of the Institute for Healthcare Improvement.

At Harvard Medical School, he is also listed as a clinical professor of pediatrics and health care policy.

Just days after passage of Democrats' health care legislation, Obama's decision to appoint Berwick to head the health care-focused agency comes.

Since Mark McClellan resigned in 2006, the agency has been without a permanent administrator.

Iowa Sen. Charles Grassley, the top Republican on the Senate Finance Committee, which will vet Dr. Berwick's nomination said, "This is always a big job, but the administration of health-care reform, which includes implementing the hundreds of billions of dollars in Medicare cuts and the biggest expansion of Medicaid in its history, will make it more challenging than ever."