WASHINGTON -- The Senate today begins debating a bill to create a $140 billion trust fund to compensate victims of asbestos exposure, including special provisions for those in Libby, Mont., after Democratic leaders backed off their attempt Tuesday to stop the measure from coming to the Senate floor.

"It's very encouraging because the first big hurdle has been cleared," said Sen. Max Baucus, D-Mont., a strong advocate of the bill. "Now it's on to the next step."

Sen. Conrad Burns, R-Mont., also praised the move but left uncertain whether he would vote for the final bill, depending on whether another Libby provision is included.

The Fairness in Asbestos Injury Resolution Act would set up a trust fund paid for by defendant asbestos companies and insurance companies to compensate those who are sick from exposure to asbestos in exchange for shielding the companies from further liability.

Democratic leaders had tried to round up enough votes for a procedural move that would have kept the bill from being considered by the full Senate. But after it became clear they did not have enough support, they dropped their objections and the Senate voted 98-1 in favor of moving to the legislation.

Now on the floor, the bill will face a contentious week of debate. It may not survive some so-called "poison pill" amendments and a possible budgetary objection that would require 60 votes to overcome.

Republican leaders and some big businesses support the bill, arguing that it would set up a fair and legal way for companies to pay without bankrupting them and for victims to receive aid. The measure has bipartisan support; its main sponsors are Sen. Arlen Specter, R-Pa., and Sen. Patrick Leahy, D-Vt.

But some insurance companies and mid-size businesses oppose the bill, contending that the financial burden is unfairly distributed and that the fund could run out of money, with the problem ending up back in court. Most labor unions and some victims groups also oppose the bill because they think it does not adequately compensate victims and will take away victims' legal rights. Trial lawyers also oppose the bill.

Payments to victims would range from $25,000 to $1.1 million.

The bill already has special provisions in it to benefit victims of asbestos exposure in Libby.

Baucus and Burns will work to add another measure to the bill including a special test, called a lung diffusion capacity test or DLCO, that they say would increase the number of people in Libby who qualify for compensation.

The test was not included when the committee approved the bill last year, with opponents arguing that it would be too expensive. Baucus is urging Specter to include the test in a manager's amendment, which he said would be the best way to assure it stays in the bill. Burns has filed it as an amendment, which Baucus also supports.

"We've got a little different challenge in Libby than we've got anywhere else in the country," Burns said. "The early sign (of the disease) is different in Libby than it is in other places."

Burns has said he would not support the bill unless the test is included, but on Tuesday said he would not make a final decision until the bill is completed. "I just don't know, we'll have to make that decision when the time comes," he said.

The bill as it currently stands already has special provisions for Libby victims. Baucus worked to included what he calls the "Libby Fix," which would exempt Libby claimants from the exposure requirements in the bill, instead requiring them to establish that they lived or worked within a 20-mile radius of Libby for at least 12 consecutive months prior to Dec. 31, 2004.

The measure would also exempt Libby claimants from the bill's medical criteria, establishing special criteria for them. The Libby claimants would be able to choose to have their claims referred to an expert physician's panel and would automatically receive a Level 4 award of $400,000 if they meet the special criteria.

A unique kind of asbestos in Libby, called tremolite asbestos, creates different health problems from the more common asbestos fibers. W.R. Grace and Co., which operated a vermiculite mine in Libby until 1990, is now in bankruptcy.

"W.R. Grace has poisoned the people of Libby, lied to the people of Libby," Baucus said. "At the very least it's only fair that the people of Libby get fair compensation and justice."

The overall bill would establish an Office of Asbestos Disease Compensation within the Labor Department. The administrator of the office, appointed by the president and confirmed by the Senate, would be responsible for managing the fund.

The administrator would establish an advisory committee, most of whose members would be appointed by Congress, and a separate medical advisory committee. The bill would also establish physician panels to make expert medical determinations.

If enacted, the bill would stay any asbestos claim pending in state or federal court unless the presentation of evidence has already begun before a jury or judge.

The bill establishes nine distinct disease levels that would result in different levels of compensation. The payments would be made over a period of three years and no more than four years, although expedited payments would be made in cases of advanced or terminal illness or extreme financial hardship.

Mesothelioma victims would be paid in one lump sum within 30 days after claims are approved or six months after claims are filed, whichever period is shorter.

The bill would also ban asbestos-containing products within one year of passage.