President Bush today nominated Stephen L. Johnson, a biologist and pathologist by training, to head the Environmental Protection Agency. Johnson, whose nomination must be confirmed by the Senate, is expected to push changes Bush wants in air pollution and clean water programs, the Associated Press reports.

A career scientist, Johnson becomes the first person in the EPA’s 35-year history to rise from within its ranks to the top job of administrator. His first task, according to AP, will be to sell air pollution regulations that are aimed at reducing mercury emissions from power plant smokestacks and other pollutants carried across state lines. These regs are due to come out within the next couple of weeks.

Johnson is also tasked with freeing Bush's top legislative priority, a "clear skies" bill that has been stalled more than two years in the Republican-controlled Senate Environment and Public Works Committee.

That measure would impose mandatory ceilings on three of the biggest pollutants from power plants — sulfur dioxide, nitrogen oxides and mercury — but allow individual plants to exceed their shares by buying pollution rights. Environmentalists say the legislation would delay needed cleanups.

"If confirmed, it will be my distinct privilege to serve you and our nation to continue to advance your environmental agenda while maintaining our nation's economic competitiveness," Johnson told Bush during a White House ceremony.

Johnson would succeed former Utah Gov. Mike Leavitt, who last month became head of the Health and Human Services Department. Johnson would take the reins of an 18,000-employee agency with an $8 billion budget.

Bush wants to cut EPA spending by nearly a half-billion dollars next year, primarily from clean water programs. He wants to reduce by one-third the low-interest loans to states for water quality protection and decrease spending on replacing aging water treatment facilities and pipes by 83 percent.

The president said one of Johnson's top jobs also would be to "lead federal efforts to ensure the safety of our drinking water supply," saying the EPA has "an important role in the war on terror."

Johnson, 53, has been with the agency 24 years. He replaced Leavitt as acting administrator in January.