WASHINGTON – Sen. Jim Jeffords of Vermont may no longer be a Republican colleague of Sen. Susan Collins, but she still can count on him to support legislation that would reduce air pollution emissions that blow into Maine.

In order to stop what she called the “dirty air express,” Collins testified in favor of tighter regulations on power plant emissions Thursday at Jeffords’ first hearing as chairman of the Senate Environment and Public Works Committee.

Jeffords left the Republican party in June, and the Democratic party thanked him by shuffling its committee rosters to give him power over the panel that oversees environmental laws.

As the easternmost state in the nation, Maine is downwind of almost all power plants in the United States, Collins said. Many of the pollutants emitted by these power plants end up in or over Maine, prompting New Englanders to charge that inexpensive electricity has come at the expense of the health of people in Maine, Vermont, New Hampshire and other downwind states.

Collins has introduced legislation with Jeffords that seeks to reduce U.S. emissions of four pollutants.

The measure would require power plants to reduce sulfur dioxide emissions by 75 percent by 2007; reduce nitrogen oxide emissions to 75 percent of 1997 levels by 2007; and reduce mercury emissions by 90 percent from 1999 levels.

The most controversial element of the bill is its provision calling for a reduction of carbon dioxide emissions to 1990 levels by 2007. Christie Whitman, head of the Environmental Protection Agency, told the committee that the Bush administration generally agrees with the first three regulations but believes more study is needed on the right level of reduction for carbon dioxide.

“On the carbon dioxide issue, it would take considerable time to get a consensus on the right level of reduction,” Whitman said. “A three-pollutant bill wouldn’t solve all of our environmental problems, but it would address some very significant public health problems. The benefits of a three-pollutant bill are too significant to delay.”

Collins, however, felt Congress had to take action on all four pollutants.

“Carbon dioxide is causing climate change that threatens to alter Maine’s delicate ecological balance,” Collins told the committee. “Airborne mercury falls into our lakes and streams, contaminating freshwater fish and threatening our people’s health. Sulfur dioxide and nitrogen oxide come to Maine in the form of acid rain and smog that damage the health of our people and our environment.”

One of the committee members who agreed the most with Collins was Sen. Hillary Rodham Clinton, D-N.Y.

“Senator Collins’ eloquent statement could have been given word for word by Sen. [Charles E.] Schumer [D-N.Y.] or myself about the pollution that New York suffers from,” Clinton said.

In a reflection of the prominence of environmental and energy issues in recent months, the committee room was overflowing with reporters, lobbyists and staffers. The discussion frequently veered toward energy production, and achieving the right balance between protection of the environment and the energy demands of a growing economy.

“Everyone in this room, everyone on this panel is the problem,” Sen. Ben Nighthorse Campbell, R-Colo., said. “We are the demand. … No one supports harming our environment, but I worry about what impact the full weight of federal government and its regulatory agenda will have on small communities.”

However, Collins was optimistic that some regulatory legislation would be passed this year by Congress.

“Today’s hearing moves us one step closer to ending the free ride for the nation’s dirtiest power plants,” Collins said. “This bill will level the playing field between upwind and downwind states.”