President Bush is naming Mark McClellan (search), chief of the Food and Drug Administration (search), to run the agency that oversees Medicare (search) and its new prescription drug benefits, administration officials said.

McClellan is a physician and economist and the brother of White House press secretary Scott McClellan.

Bush was expected to announce his nomination Friday.

McClellan will be chief of the Centers for Medicare and Medicaid Services (search), a part of the Department of Health and Human Services.