A bill to establish a $140-billion asbestos compensation fund was undergoing a rewrite on Wednesday after warnings that a provision affecting claims for silica, another lung-scarring mineral, could derail the legislation.

Senate Judiciary Committee Chairman Arlen Specter said he thought he could solve the problem and save his plan to set up a trust fund to replace asbestos litigation.

But other Republicans expressed exasperation with the process, charging Democrats were moving the goalposts each time bipartisan agreement on the fund seemed close.

“Right now I don’t think it (Specter’s proposal) has much support on the part of a number of Republicans,” Sen. Orrin Hatch, a Utah Republican and former Judiciary Committee chairman, said after a hearing on the silica issue.

“We’ve got to work out how to bring both sides together and pass a bill that has a real shot,” said Hatch.

Companies and insurers that would contribute to the fund have complained that trial lawyers are repackaging asbestos claims as injury from silica dust.

Lester Brickman, a Yeshiva University law professor, testified on Wednesday that more than half of 8,629 silica claimants in a Texas case had also filed asbestos claims.

Specter last month inserted a provision requiring claimants of injury from airborne substances other than asbestos to prove their injury was not caused by asbestos - thus keeping them from collecting twice.

But Sen. Patrick Leahy of Vermont, the committee’s ranking Democrat, said asking victims of silica to “prove a negative” was unfair. His grandfather, a stonecutter, died of silicosis, a scarring of the lungs from inhaling silica dust.

“Some special interests are trying to limit their liability on cases not related to asbestos through a last-minute, overly broad provision,” Leahy told Wednesday’s hearing.

Asbestos was used for fireproofing and insulation until the 1970s. Scientists say its inhaled fibers are linked to cancer and other diseases. Hundreds of thousands of injury claims have been filed in U.S. courts, bankrupting dozens of companies.

“It is a potential deal-breaker,” California Democrat Sen. Dianne Feinstein said of the silica provision.

Specter told interested parties to get together immediately and start trying to rewrite the silica language. “I think we are on the track to solving it,” Specter said.