Rhode Island is taking dramatic steps toward fixing one of the nation's most underfunded public pension systems, but the true battle with public-sector unions may be just beginning.

State lawmakers ignored jeers from public workers and the threat of a lawsuit Thursday to pass sweeping changes to the pension system covering 66,000 active and retired public workers.

The legislation is designed to save billions of dollars in future years by backing away from promises to state and municipal workers that lawmakers say the state can no longer afford. Gov. Lincoln Chafee, an independent, said he will sign the bill.

Public-sector union leaders promised a court challenge before the final votes were even cast.

"The attorneys are going to make a lot of money," Philip Keefe, president of Local 580, which represents social service, administrative and technical workers. "If this is overturned, it will be you, me and every other taxpayer that is on the hook for billions."

Supporters acknowledged that a lawsuit was inevitable but said the bill was thoroughly reviewed for any legal problems. Supporters said one of the reasons for the bill was to ensure there's money available when today's workers retire.