SPRINGFIELD - Roger Walker's looming ouster as the director of the state's prison system comes as no surprise - to Walker.

In an interview Tuesday, the 60-year-old former Macon County sheriff said he has not been formally notified that he's being canned after six years on the job.

But in a press conference in Chicago, Gov. Pat Quinn told reporters he would likely replace Walker later this week.

"I pretty much knew they were going to do this," Walker said. "You work at the pleasure of the governor."

Walker, who earns $150,400 annually, is among a handful of agency directors on the hot seat in the wake of Quinn taking over for disgraced former Gov. Rod Blagojevich.

Quinn has replaced directors at the Department of Natural Resources and the Illinois State Police as part of what he calls his efforts to "fumigate" government in the wake of Blagojevich's removal from office.

The governor did not say who will take over the sprawling, billion-dollar agency.

Walker will leave behind a legacy of operating the department with fewer employees. Blagojevich's efforts to reduce state payroll costs left many prisons understaffed, forcing the state to spend more than $60 million this year on overtime for guards and other employees.

During his tenure, Walker also worked, but failed, to close two state prisons at the request of Blagojevich. His efforts to fully open Thomson Correctional Center also fell short.

Walker has been on medical leave for nearly two months for undisclosed heath reasons. He had stomach-related surgery and has been recovering at home.

He said the therapy is "coming along."

"That's the main thing with me right now, my health," Walker said.