Jackson’s opening statement at her Senate confirmation hearing was the clearest signal yet that the Obama administration plans to take the agency in a different direction. The Bush administration at times ignored the advice of scientific experts on decisions ranging from global warming to air pollution.

“Science must be the backbone of what EPA does,” said Jackson. “EPA’s addressing of scientific decisions should reflect the expert judgment of the agency’s career scientists.”

The Senate Committee on Environment and Public Works is also considering the nomination of Nancy Sutley, Obama’s choice to chair the White House Council on Environmental Quality.

Sutley also vowed to rely on science as she helped to “move the nation to greater reliance on clean energy and increase energy security.”

Senators are expected to press both candidates for details on how the incoming administration plans to tackle global warming and water pollution. They also could be asked whether they plan to redo Bush administration rules that Senate Democrats say have weakened environmental protections.

Obama has called for legislation to curb the gas emissions blamed for global warming. But it is unclear whether he will pursue a new law first or use existing statutes to more quickly address the problem. He could immediately grant states like California the right to regulate emissions from automobile tailpipes, or trigger controls under the Clean Air Act.

Democrats will want Jackson, the former head of New Jersey’s environmental department, to commit to regulating the disposal of toxic coal ash after two recent spills at power plants in Alabama and Tennessee.

If confirmed, Jackson, 46, would be the first black person to lead the EPA – an agency with 17,000 employees and a $7 billion budget.

Before running the New Jersey Department of Environmental Protection, Jackson worked at the EPA for 16 years. She served under Carol Browner, President Bill Clinton’s EPA chief and Obama’s pick for a new White House position coordinating energy and climate policy.

Sutley, 46, is the deputy mayor for energy and environment in Los Angeles. She is the daughter of Argentinean immigrants and is a gay rights activist. She also worked at the EPA during the Clinton administration.

If confirmed, Sutley will coordinate energy and environmental policy from the White House.

Lisa Jackson, picked to head the Environmental Protection Agency, and Nancy Sutley, tapped to chair the White House Council on Environmental Quality, were expected to be endorsed by the Senate Environment and Public Works Committee, where they were to appear for a confirmation hearing Wednesday.

The candidates will be pressed for details on how the incoming administration plans to tackle global warming and water pollution. They also could be asked whether they plan to redo Bush administration rules that Senate Democrats say have weakened environmental protections.

Obama has called for legislation to curb the gas emissions blamed for global warming. But it is unclear whether he will pursue a new law first or use existing statutes to more quickly address the problem. He could immediately grant states like California the right to regulate emissions from automobile tailpipes, or trigger controls under the Clean Air Act.

Democrats will want Jackson, the former head of New Jersey’s environmental department, to commit to regulating the disposal of toxic coal ash after two recent spills at power plants in Alabama and Tennessee.

Committee Chairwoman Barbara Boxer, a California Democrat who has called for the resignation of the current EPA administrator, said, “This is a day that I have been waiting for a very long time.”

Republicans were not expected to fight confirmation of the nominees. An aide to Oklahoma Sen. James Inhofe, the top Republican on the panel, said the senator met with Jackson last week and was impressed with her credentials.

Sutley, 46, is the deputy mayor for energy and environment in Los Angeles. She is the daughter of Argentinian immigrants and is a gay rights activist. She also worked at the EPA during the Clinton administration.

If confirmed, Sutley will coordinate energy and environmental policy from the White House.

If confirmed, Jackson, 46, would be the first black person to lead the EPA – an agency with 17,000 employees and a $7 billion budget.

Before running the New Jersey Department of Environmental Protection, Jackson worked at the EPA for 16 years. She served under Carol Browner, President Bill Clinton’s EPA chief and Obama’s pick for a new White House position coordinating energy and climate policy.

Sutley is the first prominent member of the LGBT community to earn a senior role in the Democrat’s new administration. Speculation began circulating a week ago that she would be named to the post.

Sutley, 46, holds a bachelor’s degree in government from Cornell University and a master’s in public policy from Harvard.

From 1999-2003 she was a special assistant to EPA administrator Carol Browner.

Following that, she served until 2005 as deputy secretary for policy and intergovernmental relations at the California Environmental Protection Agency and energy adviser to Gov. Gray Davis.

Currently Sutley is a Deputy Mayor of Los Angeles for Energy and Environment and a board member for the Metropolitan Water District of Southern California.

Sutley supported Sen. Hillary Rodham Clinton during the Democratic primary and was a member of her LGBT steering committee.

“President-elect Obama’s nomination of Nancy Sutley is another step toward full equality for gay Americans,” Chuck Wolfe, president of the Gay & Lesbian Leadership Institute, said in a statement.

“It sends a signal to young people that they can participate in their government at its highest levels, regardless of their sexual orientation, gender or ethnicity.”

Obama also announced the other members of his Environmental and Energy team.

He said he will nominate Sen. Ken Salazar of Colorado to run the Interior Department. Nobel-prize winning physicist Steven Chu will be energy secretary, and Lisa Jackson, the former head of New Jersey’s environmental department, will head the Environmental Protection Agency.

Carol Browner, a confidante of former Vice President Al Gore, will lead a White House council on energy and climate. Browner headed the Environmental Protection Agency in the Clinton administration.

In making the announcments Obama made clear he plans take energy policy in a sharply different direction from President George W. Bush, promising aggressive moves to address global warming and support research into alternative energy sources such as wind, solar and biofuels.

“America must develop new forms of energy and new ways of using it,” he said.

Obama said the dangers of being too heavily dependent on foreign oil “are eclipsed only by the long-term threat of climate change which, unless we act, will lead to drought and famine abroad, devastating weather patterns and terrible storms on our shores, and disappearance of our coastline at home.”