House and Senate Republicans were unable to reach an agreement Thursday on a handful of conflicts that have blocked agreement on energy legislation, despite the direct intervention of top GOP leaders.

"We're really getting close," Sen. Pete Domenici (search), R-N.M., chairman of the energy talks, told reporters after what had been billed as a make-or-break meeting.

Rep. Billy Tauzin (search), R-La., said a final package is "within a hair's breadth" of being approved. While not elaborating, they said several issues remained to be ironed out.

But it was learned that House Speaker Dennis Hastert (search) of Illinois and Senate Majority Leader Bill Frist of Tennessee were assuming a more direct role in trying to work out a compromise over the future of the gasoline additive MTBE, including whether to give its manufacturers liability protection from environmental lawsuits.

The GOP-dominated energy talks have been at loggerheads over the MTBE issue for several weeks. The additive is being phased out in many states because it has fouled drinking water supplies.

The issue has been difficult to overcome because House Majority Leader Tom DeLay of Texas, where most of the MTBE is made, has dug in his heels in favor of the liability waiver. At least 43 senators wrote a letter to Domenici and Tauzin this week asking the MTBE protection be rejected.

Frist and Hastert stepped in this week to try narrow the differences in the handful of issues that have prevented completion of the more-than-800-page bill. They and the White House want a bill to vote on by next week.

In addition to the MTBE dispute, the talks have been held up over:

—The extent of tax breaks for a proposed $20 billion Alaska natural gas pipeline.

—Who should pay for construction and improvements of certain high-voltage power lines and how much say the federal government should have in designing electricity markets.

Neither issue has been totally resolved, participants said late Thursday.

Another area of concern has been a provision in the GOP draft that would open the Arctic National Wildlife Refuge in Alaska to oil drilling. Senate Democrats said they will filibuster the energy legislation and prevent its final approval if ANWR drilling is included.

Domenici, who has said he would not allow the ANWR issue to threaten final approval of a bill, said Thursday no decision on ANWR had yet been made. Frist has also made it known he wants the provision scrapped if it jeopardizes the legislation.

Republicans have the votes to fashion the bill largely to their liking, despite Democratic objections. Once the negotiations between the House and Senate produce a bill, it will be given a final vote in both chambers, but cannot be changed.

The legislation includes at least $16 billion in tax benefits, mostly to promote greater production and use of coal, natural gas, domestic petroleum resources and nuclear power.

The draft also includes measures that would improve the nation's electric power grid, expand use of corn-based ethanol for gasoline, grant greater access to energy sources on federal land and authorize construction of a pipeline to get massive amounts of natural gas on Alaska's North Slope to the lower 48 states.

While there is agreement on the need for tax incentives and loan guarantees for building the pipeline, House Republicans and the White House have balked at the insistence of Alaska's two senators that Alaska gas be given a tax credit that would kick in if natural gas prices fall below a certain level.