While specifics are being debated, Bush administration officials said they think they need to act now rather than risk more regulation in the future, The Washington Times said.

"This is an attempt to move the administration and the party closer to the center on global warming. With these steps, it is hoped that the debate over this is over, and it is time to do something," a source told the Times.

Congressional members told administration officials that an environment-related measure could lead to runaway legislation in the Democratically controlled Congress, the source said.

Environmentalists say greenhouse gases can be regulated under the Clean Air Act, the Endangered Species Act or the National Environmental Policy Act, and they have filed lawsuits to try to force action. The Bush administration said it wants to avoid the tangled rules and regulations for businesses.

"The embedded regulatory trajectory that we're on is a train wreck," White House spokeswoman Dana Perino said. "For those who want reasonable and responsible action, it is worthwhile to have a constructive conversation."