HARRISBURG -- Gov. Ed Rendell went to Washington, D.C., yesterday to fight for tougher clean air standards for Pennsylvania and other states.

He appeared before a Senate committee that seemed sympathetic to his plea, but in the end he wasn't successful in getting federal Environmental Protection Agency Administrator Stephen L. Johnson to agree.

Four years ago, California, where air pollution is a major problem in many cities, led the way by enacting strict standards for reducing "greenhouse gas emissions," called the California Low Emission Vehicle program.

Pennsylvania and 11 other states have since joined California in trying to enact similar tough rules against air pollution. California has asked the Bush administration for a waiver to implement its rules, which are stricter than federal rules, saying the air pollution problem in California requires a tougher approach.

"We stand firmly with California in its effort to continue fighting for this waiver," Mr. Rendell told the U.S. Senate Committee on Environment and Public Works yesterday.

Under the Clean Air Act, California needs the federal waiver to allow the state to implement its first-in-the-nation tailpipe law. That would force auto makers to reduce greenhouse gas emissions by 30 percent in new cars and light trucks by 2016.

Mr. Rendell said the 30 percent cut in "climate-changing greenhouse gas emissions ... is very important to us" in Pennsylvania. That amount of pollution reduction "exceeds what Pennsylvania can expect to realize" under a recently approved federal act.

Starting with the 2008 model year, Pennsylvania wants to start implementing the requirement that only light-duty trucks and passenger cars that have been certified by California be sold in Pennsylvania, Mr. Rendell said. But so far that plan has been blocked.

"California's request for a waiver will provide better protection for public health and the environment than the federal rule would do," Mr. Rendell said. "Pennsylvania is relying on these emission reductions over the long term to maintain ozone air pollution at healthy levels [and] to cultivate a stronger economic environment."

But Mr. Johnson said he doesn't want a patchwork of different air pollution standards from state to state. He said it's better to have a single national standard for greenhouse gas emissions. He denied that he was caving in to "special interests," such as car companies, or political pressure from the White House.

He said the federal Clean Air Act "does not require me to rubber-stamp waiver decisions."

If California can get the federal waiver for stricter air pollution standards, other states, including Pennsylvania, Connecticut, Maine, Maryland, Massachusetts, New Jersey, New Mexico, New York, Oregon, Rhode Island, Vermont and Washington, would implement them also. They are suing EPA over Mr. Johnson's decision.

Mr. Rendell said it is "disheartening and disappointing" that President Bush and the EPA "would make such a narrow-minded and short-sighted decision" to deny the greenhouse gas waiver request from California and other states.