Leavitt, 53, would succeed the post vacated by Tommy Thompson, who recently resigned amidst a widespread shake-up of the president's cabinet before Bush commences his second term. “I feel a real sense of understandable regret," said Leavitt about leaving the EPA.

Having administered the EPA for just over a year, the former Utah governor won a reputation at the agency as a Bush loyalist and shared the president's enthusiasm for technological and market-based approaches to fixing environmental problems. Under his administration, the EPA worked to regulate mercury emissions and oversaw the formation of the Clean Diesel Retrofit Program and international Methane to Markets Partnership. The agency's FY 2004 enforcement secured cleanups worth a record $4.8 billion, preventing about one billion pounds of pollution.

As of yet, no successor has been named, pending Leavitt's approval as HHS Secretary.