It was Bush's second event in two days aimed at bolstering his environmental record for his re-election campaign, and at defending an air-quality agenda that environmentalists believe threatens increased pollution.

"Every chance they (the Bush administration) get to side with the corporate polluters at the expense of the environment and the public's health, they take it," said New Jersey Democratic Sen. Frank Lautenberg.

Bush visited a power plant in Monroe, Michigan on Monday, to promote a controversial change in clean air rules that makes it easier for industrial facilities to install new equipment without updating pollution controls.

Yesterday, he focused on his proposed "Clear Skies" legislation of new standards for industrial air pollution.

The plan would limit emissions of sulfur dioxides, nitrogen oxide and mercury and assign companies emissions permits, which could be bought and sold.

Environmentalists say the proposal fails to regulate emissions of carbon dioxide, believed to contribute to global warming, and that its standards are weaker than existing law.

"If Congress passed the Clear Skies bill, the result would be to weaken and delay health protections already required under the current law," the Natural Resources Defense Council said on its Internet site.

Bush declared the proposal would reduce emissions by 70 percent and encourage investment by reducing uncertainty and giving companies an incentive to reduce pollution so they could sell their emissions permits.