COLUMBUS, Ohio -- The Ohio House and Senate plan to vote Wednesday on a budget bill that would freeze Medicaid expansion enrollment next year, a move Gov. John Kasich's administration says would result in 500,000 low-income Ohioans losing health insurance coverage.

More than 725,000 Ohioans have received coverage through Medicaid, the joint state-federal health insurance program for poor and disabled Americans, since the state expanded eligibility in 2014 to those making up to 138 percent of the poverty level.

The budget bill, finalized late Tuesday night, would freeze enrollment after July 1, 2018, with exceptions for people receiving treatment for alcohol or drug addiction or mental illness. The state would have to obtain a waiver to do so.

The provision was one of 612 reviewed by a six-member conference committee working on a compromise between the House and Senate versions of the bill. The bill was reported out of committee late Tuesday along party lines, with the two Democrats voting against the changes.

More than 500,000 people enrolled through the expansion would lose coverage within 18 months of a freeze, not accounting for the mental illness or addiction exemptions, according to a memo from Kasich's Office of Health Transformation.

That's because many people lose and gain eligibility several times a year as they find or lose work, especially seasonally. After July 1, former expansion enrollees couldn't sign up again when their income falls.

Earlier on Tuesday, Kasich was in Washington, D.C. touting benefits of the expansion in his opposition to the U.S. Senate's health care bill. Kasich said most people enrolled through the expansion only receive coverage for about 18 months before they get better jobs, representing a conservative ideal.

Reducing Medicaid eligibility could cut into the state's efforts fighting Ohio's opioid addiction and overdose crisis. Of the $940 million the state spends on those efforts each year, about $650 million is through Medicaid, including $279 million through the expansion.

Kasich could use his line-item veto to undo the freeze; the votes of three-fifths of the General Assembly would be needed to override such a veto. Kasich must sign the budget into law before the new fiscal year begins July 1.