Backers plan to introduce a motion yesterday for the Senate to immediately begin consideration of the matter, aides said. If it passes, as expected, there would be up to 10 hours of debate before a vote is held on the $58 billion project, also likely yesterday, aides said.

"We have a firm majority," one Republican aide said.

"There is ample support to get this done," another Republican aide said.

"They do seem to have the votes," conceded an aide to a Democratic senator expected to endorse the proposal yesterday over the objections of the state of Nevada, which is challenging it in court, citing safety concerns.

A Senate Republican leadership aide said, "A lot of senators are going to vote for Yucca because if they don't they know the nuclear waste could end up in their states."

Sens. Bob Bennett and Orrin Hatch, both Utah Republicans, announced this week they would back the Yucca project after they were warned in a letter from U.S. Energy Secretary Spencer Abraham that if the facility was rejected, nuclear waste would likely be stored at a temporary site in their state.

Senate Majority Leader Tom Daschle, a South Dakota Democrat, sent a letter to Bush this week urging him to tell Senate Republicans to delay a vote on Yucca Mountain until the chamber completes work on a bill to crack down on the recent spate of corporate scandals.

UPHILL BATTLE

But Senate Republican leaders decided to push ahead and work with Democrats to reduce the amount of debate on the measure, aides said.

"We always knew this would be an uphill battle," said Tessa Hafen, a spokeswoman for Sen. Harry Reid, a Nevada Democrat who has helped lead the charge against it. "But we haven't given up," Hafen said. "Senator Reid is still working the phones and the Senate floor."

Final congressional approval would clear the way for the U.S. Energy Department to apply to the Nuclear Regulatory Commission to license the project, scheduled to open in 2010 and hold 70,000 tons of radioactive material.

The Senate will vote on a resolution to override Nevada Gov. Kenny Guinn's veto in April of Bush's decision to accept a recommendation by Abraham to build the facility in Nevada.

A similar resolution passed the Republican-led House of Representatives in May on a bipartisan vote of 306-117.

Nuclear power plants produce more than 20 percent of the country's energy. The so-called spent fuel from those plants is highly radioactive and is being stored in tanks usually on the plant site. Many of those waste storage tanks are nearly full. The government has faced lawsuits for failing to meet a 1998 deadline to open a permanent nuclear waste storage site.

In addition to Nevada, the Yucca project has been opposed by a number of environmental and public interest groups who agree with the state that it would be a hazard.

But the Bush administration contends $4 billion in studies over the past two decades have shown Yucca Mountain to be a safe and sound site for a nuclear waste repository.

On June 5, the Democrat-led Senate Energy Committee gave its blessing to the project on a 13-10 vote. Among those who voted for it was committee Chairman Jeff Bingaman, a New Mexico Democrat.