Iowa lawmakers have reached a tentative agreement on education spending and plan to introduce a bill that would represent the largest commercial property tax cut in state history, a key negotiator said Thursday while acknowledging "sharp differences" in other areas of the budget.

Legislative leaders continued closed-door budget talks on a massive spending bill for state health care services, agriculture and natural resources, and other budget items. But Senate Majority Leader Mike Gronstal told reporters he was optimistic about the progress made, and said lawmakers are on pace to end their session by the middle of next week.

"When we're all done, we're all going to be a bit pleased -- and we're all going to be a bit disappointed," said Gronstal, D-Council Bluffs.

All commercial property in Iowa would receive a tax cut under the bill, with nearly two-thirds seeing a 40 percent reduction. Local governments would be reimbursed for lost property-tax revenue. The legislation would also more than double the state's earned income tax credit, and cut property taxes on apartments.