More than a dozen insurance companies have dropped their support for a $140 billion federal trust fund to pay claims stemming from asbestos-related lawsuits, The Wall Street Journal reported on Tuesday.

The move makes it less likely that Congress will approve legislation on the subject this year, the newspaper said, leaving hundreds of U.S. companies unsure how much money they owe in asbestos claims.

The insurers, which have complained the fund would be too large and would not adequately limit their liability, told Senate Judiciary Committee Chairman Arlen Specter in a letter on Monday that the plan is “unfixable,” the Journal reported.

The group of insurers withdrawing support for the fund includes American International Group Inc., Chubb Corp. and Zurich Financial Services, the paper said.

The insurers, in the letter, said they “have become increasingly skeptical that a trust fund can ultimately provide the certainty and finality all parties seek,” the Journal reported.