A proposed deal brokered by top Illinois officials to reform the state's beleaguered public pension system was assailed by unions, which called the plan unconstitutional.

A coalition of unions representing a million members said proposed reductions in cost of living adjustments and changes to the retirement age were unconstitutional because they ignore collective bargaining rights. The We Are One Illinois group urged the million members it represents to call their state representatives and implore them to vote against the plan.

Under the deal reached by leaders from both parties, the retirement age would be gradually raised for current worker under 45. Some workers can retire at 58. That would be raised as much as five years, depending on the plan. Cost of living raises would be tied to inflation and would be calculated using a formula designed to benefit workers receiving smaller benefits.