Four panel members seen as possible swing votes asked the Bush administration and Inhofe for more data on how the plan compares with competing legislation and current law.

"It is imperative that we have the most up-to-date information available in order to effectively negotiate a bipartisan compromise," said a letter to Inhofe signed by Democrats Max Baucus of Montana, Tom Carper of Delaware and Barack Obama of Illinois and Republican Lincoln Chafee of Rhode Island.

Lawmakers met with Inhofe late on Tuesday and "realized they were closer than they thought on many issues" but needed more time, an Inhofe spokesman said.

Inhofe says time is running short to advance the plan, which would cut three major pollutants spewed by coal-burning power plants by 2016 through a cap-and-trade system.

A delayed panel vote could dampen the bill's prospects for passage this year.

Inhofe says he faces a March 15 deadline to get the legislation passed by his panel because of a consent decree the Bush administration signed with the Natural Resources Defense Council, an environmental group challenging the rules.

"The point at which we couldn't move further in the committee is March 15," Inhofe's spokesman said.

Panel Democrats and Chafee oppose the bill because it lacks a limit on carbon dioxide, a greenhouse gas linked to climate warming.

They also say the legislation's targeted emission cuts are too weak and give utilities too much time to install expensive pollution-reduction equipment.