CHICAGO (AP) — Illinois’ largest union and Gov. Pat Quinn’s administration reached a tentative contract agreement Thursday, averting the threat of the first state worker strike in decades.

Details of the three-year agreement with the American Federation of State, County and Municipal Employees Council 31 were not made public.

“Our members have to have an opportunity to review the tentative agreement and discuss,” said Anders Lindall, the spokesman representing the union with roughly 35,000 members.

He said an agreement was reached after midnight and members would begin reviewing the proposal next week for ratification. The union has been working without a contract since November.

The union and Quinn’s office had been negotiating for more than a year at a time when the relationship was already strained. AFSCME issued a memo in February to members telling them how to prepare in case of a possible strike and worker protests in recent months had called on Quinn for fair employment and collective bargaining practices.

There hasn’t been a state employee strike since the 1973 advent of collective bargaining. A walkout could have included child-abuse investigators and those who care for the elderly, according to union officials. Illinois law prohibits strikes by security workers.

Quinn had wanted workers to accept a multiyear wage freeze along with changes in health care coverage. AFSCME Council 31 Executive Director Henry Bayer said those changes would cost each employee an additional $10,000 over the length of the contract.

Neither side would talk details of the agreement Thursday, except to characterize it as fair considering the state’s fiscal woes.

“At a time when the state is facing unprecedented financial challenges, this agreement is fair to both hard-working state employees and all taxpayers of Illinois,” Quinn said in a statement.

Illinois has the worst-in-the-nation pension problem with nearly $100 billion in unfunded liability. The union opposes reductions to their retirement benefits and increases to their health insurance costs, which have been central themes on pension overhaul talks. Also, union members had fought state facility closures and are angry that Quinn withheld pay raises provided by the last contract, an issue has been tied up in the courts.

Union officials said once members had a chance to review the agreement more details would be released.

“AFSCME is very pleased that we were able to reach an agreement that protects our members’ standard of living, and is fair to them and all Illinois citizens, even in these very challenging economic times,” Bayer said in a statement.

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