Sen. Pete Domenici (Republican-New Mexico), who is short of the 60 votes needed to end debate on the $31-bil measure, told reporters he has until March to come up with additional support.

"I'm worried that on the pure energy production side there's just so many good things that I hate to dismantle this bill thinking we're going to get these three pieces but not the other eight," Domenici said.

The senator added there is discussion about moving the ethanol provisions in the energy legislation to a multi-billion dollar highway bill expected to pass the Congress this year. The "renewable fuels standard" favored by a majority of House and Senate lawmakers would require 5-bil gal of ethanol be blended in gasoline by 2012.

US Senate Majority Leader Bill Frist (Republican-Tennessee) said he was not confident the Senate would approve the energy bill, which has been a top priority for President George W. Bush since 2001.