Richard Foster, Medicare's influential chief actuary, will retire in January, the Obama administration announced Friday.

For the past 18 years, Foster oversaw the CMS' estimates of national healthcare expenditures and led a team of 100 that gathered data for determining Medicare payment rates for hospitals, physicians, dialysis and other pre- and post-acute-care facilities.

Foster came under fire from the Bush administration in 2003 because he publicly warned about the cost of adding a prescription drug benefit to the program. The CMS will conduct a national search for his successor, the New York Times reported.