SPRINGFIELD — Illinois officials saw a surge in retirements last month as workers tried to lock in their pension benefits before an overhaul of the state's underfunded retirement systems goes into effect on June 1.

Timothy Blair, executive director of the State Employees Retirement System, said an estimated 1,100 workers were on track to retire during the month of April, compared with a normal number of about 200.

Final tallies were not available Thursday.

By retiring in April, some workers think they may be able to lock in their pensions at pre-overhaul levels, pending the outcome of a series of lawsuits seeking to kill the changes.

Blair said there is no way to know if the strategy will work. But, he said, "The potential upside is there, and there's not a lot of downside for someone who is close to retiring anyway."

The rush for the exits by prison guards, General Assembly secretaries, laborers and other state workers comes in response to the passage of Senate Bill 1 in December, reducing benefits for employees and retirees in an effort to save $145 billion.

The law puts limits on annual cost-of-living increases and raises the retirement age, for example.

Lawsuits claiming that the moves violate the state Constitution are pending in Sangamon County court. Gov. Pat Quinn's administration and other defendants are scheduled to respond to the suit on May 15.

Anders Lindall, spokesman for the American Federation of State, County and Municipal Employees Council 31, said the increase in retirements is not a surprise.

"It's indicative of the harm done to employees and retirees and the complications posed by the implementation of Senate Bill 1," Lindall said.

It's not just state workers who are leaving the workforce because of the changes.

Thousands of university employees also are retiring sooner than they expected because of a mistake in Senate Bill 1 that calculates a university employee's benefits as of last year instead of this year.

Lawmakers have pledged to fix the mistake, but that hasn't stopped the departures.

Sen. Chapin Rose, R-Mahomet, said he understands why people are leaving their jobs but bemoaned the situation.

"There is a brain drain that is happening here," Rose said. "But I think people are thinking a bird in the hand is worth two in the bush."

Added Lindall, "We hope the legislation will be overturned to avoid the harm to employees who are having to make major life decisions."