Several lawmakers said Thursday they would try to prevent a House energy plan that seeks to block California and other states from regulating tailpipe emissions.

During a hearing, several House Democrats joined opposition from House Speaker Nancy Pelosi (news, bio, voting record), D-Calif. They said they could not back legislation that would limit California's efforts to reduce greenhouse gas emissions or the Environmental Protection Agency's ability to regulate them.

"This bill is cutting the legs out from under the states just as they are starting to sprint forward on carbon pollution regulation," said Rep. Edward Markey (news, bio, voting record), D-Mass.

Reps. Jane Harman (news, bio, voting record) and Henry Waxman (news, bio, voting record), D-Calif., said they support a proposal next week that would attempt to strip away the provision preventing California from regulating the vehicle emissions.

The comments came at the start of a lengthy hearing on a comprehensive energy plan that would propose that the auto industry meet gas mileage standards of at least 36 miles per gallon for passenger cars after 2021 and 30 mpg for trucks after 2024. It would also create a low-carbon fuel standard and push the auto industry to boost their production of vehicles running on alternative fuels such as ethanol.

California has asked the federal government for a waiver for two years to implement a state law that would cut greenhouse gas emissions, mostly carbon dioxide, by 25 percent from cars and 18 percent from sport utility vehicles beginning in 2009. At least 11 other states are ready to follow California's lead.

The House bill, drafted by Rep. Rick Boucher (news, bio, voting record), D-Va., would prohibit the EPA from issuing a waiver a state would need to impose auto pollution standards if the new requirements are "designed to reduce greenhouse gas emissions."

Gov. Arnold Schwarzenegger of California and the governors of Arizona, Massachusetts, New Mexico, New York, Oregon, Pennsylvania and Washington released a letter to Boucher on Thursday opposing the plan. "Congress must not deny states the right to pursue solutions in the absence of federal policy," they wrote.

Some lawmakers said the bill would also attempt to overturn the findings of a Supreme Court decision in April that said the EPA has the authority to regulate greenhouse gases from cars and trucks. But supporters of the bill said it would preserve the ability of states to regulate toxic air pollutants from motor vehicles.

Boucher, who heads a House Energy and Commerce subcommittee that is developing the plan, has said it is important to have "unified regulations" for sources of carbon dioxide emissions. During Thursday's hearing, he said it would "respond to the regulatory confusion" following the Supreme Court decision.