Monique Bond, an ISP spokeswoman, says instead existing officers will have to work overtime.
"We will definitely most likely continue to have to grapple with overtime because we don't have the resources. The overtime costs can be very costly, however we have no choice. We will not compromise safety and security."
Governor Pat Quinn has not yet signed the budget, but he is expected to do so before the start of the new fiscal year, which begins July first.