University of Illinois Hospital nurses voted by a wide margin to authorize a strike if their union and the West Side hospital system are unable to come to terms on a new contract by late September.

The nurses, members of the Illinois Nurses Association, had a three-year contract with the hospital system that was recently extended to Sept. 23 after the two sides were unable to agree on a new pact.

The measure voted on Monday and Tuesday, which 93 percent of nurses approved, was described by organizers as “a procedural move” that the union has used before in negotiations with hospitals and other organizations. They’d have to vote again for the work stoppage to go into effect, according to the union. Any strike wouldn’t begin until after the contract expires.

Wages are among the sticking points on the negotiations, which have now moved under the guidance of a federal mediator. The nurses also are seeking other protections on staffing and scheduling.

The union represents about 1,150 nurses in the health system, which operates a 495-bed academic medical center and is headquartered on Taylor Street on the campus of University of Illinois at Chicago.

Hospital officials said the nurses are seeking a 21.5 percent wage increase over three years, a hike hospital administrators said would cost the system $20 million. Nurses, meanwhile, say the hospital has offered a 1 percent raise per year, less than the rate of inflation.

University of Illinois Hospital nurses earned an average of $106,000 in 2013, 27 percent more than the Chicago market average salary, according to the hospital system. 

The nurses also are seeking other protections on staffing and scheduling. They said the hospital system is seeking 23 concessions from them, affecting “everything from staffing to nurses’ basic union rights,” the union said in a statement.

Like other hospital systems, the University of Illinois Hospital is facing revenue declines as more care shifts to outpatient settings and the government and commercial insurers exert more pressure on reimbursement.

The system reported unaudited revenue of $809.8 million in fiscal 2014, down from $814.7 million in the previous year.

In a letter to hospital staff, the system’s CEO, Avijit Ghosh, said the administration is “committed to the principle that all our employees should receive competitive wages reflecting industry norms.”

“I feel confident that we can resolve these issues amicably as we continue to work together for the benefit of our patients,” Ghosh said.

pfrost@tribune.com