The Democrats who will steer environment issues in the new Congress are polar opposites of their Republican predecessors, but changing environmental policy is like turning around an aircraft carrier — it's very slow.

Sen. Barbara Boxer, a liberal California Democrat and one of the biggest environmental advocates on Capitol Hill, was named Tuesday to chair the Senate Environment and Public Works Committee. She replaces Oklahoma Republican James Inhofe, who says global warming is a hoax and wanted to abolish the Environmental Protection Agency established by President Richard Nixon.

On the House side, the approach to endangered species and opening public lands to private development will do an about-face with Rep. Nick Rahall, D-W.Va., expected to take over the House Resources Committee. He would replace GOP Rep. Richard Pombo, a California rancher, defeated for re-election last week after environmentalists spent nearly $2 million against him.

"Our long national nightmare is close to being over," said Philip Clapp, president of the National Environmental Trust, paraphrasing Gerald Ford on assuming the presidency after Nixon's resignation over Watergate.

Democrats will focus on cutting pollution blamed for global warming, accelerating toxic waste cleanups, reversing Bush administration tax and regulatory breaks for energy producers and switching the government's course back to strict protections for endangered species.

Their environmental allies are back on offense. "We've been forced to play defense most of the past six years," said Gene Karpinski, president of the League of Conservation Voters.

Energy companies will likely be put on the defensive. Rep. Nancy Pelosi, D-Calif., the presumed next speaker of the House, has already promised to repeal oil industry subsidies.

Rep. John Dingell, D-Mich., the likely next chairman of the House Energy and Commerce Committee, plans to investigate Republicans' oil subsidies included in the energy bill Bush signed into law last year. Dingell said he also was interested in revisiting Vice President Dick Cheney's secretive energy task force.

Environmentalists say any global warming policy must be accompanied by higher fuel economy standards for cars and light trucks. On that issue, they worry that Dingell, who represents thousands of auto workers and is a strong ally of the auto industry, could stand in the way.

Dingell has opposed raising those standards because of concerns that jobs could be lost and automakers might suffer even more than they are now economically.

Among Boxer's first moves will be a bill to curb greenhouse gases, modeled after her home state's approach which seeks to lower emissions to 1990 levels by 2020.

"Some of the practical solutions are in the California approach" of Republican Gov. Arnold Schwarzenegger, she said.

Already, John McCain of Arizona and other Republican senators have proposed bills or expressed support for mandatory caps on the U.S. fossil fuel-burning emissions of carbon dioxide.

Even some Republicans say that President Bush might eventually agree to address global warming by imposing a nationwide cap on greenhouse gases. A system for companies to swap the rights to pollute would be established under the cap.

That would require a second 180-degree reversal of his stance on global warming. He entered office in 2001 pledging to regulate industrial carbon dioxide emissions but came out against regulation shortly afterward. To date, Bush has favored voluntary strategies and more research and development.

"The president has indicated that a market-based cap is on his list of options. And it's pretty high on the list; it's in second place," said Tucker Eskew, a Republican consultant and former Bush White House aide.

It wouldn't be the first time Bush signed a bill about something he at first opposed.

Last month, Bush signed a law to build 700 miles of fence on the U.S.-Mexico border though he had wanted a broader approach that gave some illegal immigrants citizenship. In 2002, he agreed to fold nearly two dozen agencies into a new Homeland Security Department after opposing it for nine months.

Boxer also plans hearings on her longstanding complaint that the EPA has maintained a sluggish pace in cleaning up Superfund toxic-waste sites. The EPA says the sites are getting bigger, costlier and more complex to remedy.

Looking to 2008, strategists in both parties see great opportunity in the environment.

"Any candidate who allows himself to be recklessly out of touch with mainstream environmental values is vulnerable," said Carl Pope, the Sierra Club's executive director.