(CNN) Utah voters approved Medicaid expansion last November, but Republican state representatives -- who have long opposed broadening coverage for low-income residents -- are now moving to limit the extent of the changes.

The state Senate could vote as early as Monday on a bill that would restrict coverage to those at or below the poverty line, instead of up to 138% of that threshold, as is standard under the Obamacare provision to expand Medicaid. It's expected to pass the GOP-controlled Utah House and Gov. Gary Herbert, a Republican, is likely to sign it.

It would also mandate beneficiaries to work, place a per-capita cap on spending and impose a lock-out period for those who violate certain requirements. And the bill would close the program to new enrollees if costs are projected to exceed the funds the legislature appropriated, said Republican state Sen. Allen Christensen, who sponsored the measure.