DES MOINES, Iowa — A top Iowa regulator on Tuesday expressed reservation about the future of a proposal that would allow the state to redirect Affordable Care Act money to lower some people’s health insurance costs, noting he had expected the federal government to issue a decision by now on the ambitious plan.

Iowa Insurance Commissioner Doug Ommen told lawmakers during a meeting at the state Capitol that he’s still hopeful the Centers for Medicare and Medicaid Services will approve the so-called stopgap measure for the state’s individual insurance market. But he also indicated he had expected a decision amid a looming deadline on open enrollment for ACA coverage.

“We wanted to know for today whether or not we were going to obtain approval. I guess I’m less optimistic having not heard,” he said.

Centers for Medicare and Medicaid Services declined to comment, directing inquiries about the proposal to an agency website that provides status updates.

Under the ACA, an individual receives federal government subsidies to purchase health insurance that’s based on a certain percentage of one’s income. Under the stopgap proposal, Iowa would use some of those subsidies to offer a single, standard insurance plan that provides premium credits based on certain age and income factors.

More people would be eligible for credits, with the goal of enticing younger and healthier residents who currently make too much money to qualify for federal subsidies to buy coverage. Critics argue that will shift costs to low-income and older participants, since some people whose costs are currently capped will see an increase in what they must pay.

Ommen has argued some concerns about costs are “valid” but the threat of thousands leaving the market if nothing is done is also real. He has pointed out that the state adjusted its proposal on premium credit levels to better help individuals who may have new out-of-pocket expenses.

The plan, first submitted to the federal government in June and finalized last month, would be in effect for 2018. It also develops a program to help carriers with high-cost patients.

About 72,000 people are enrolled in Iowa’s individual health insurance market. Ommen used an actuarial study to estimate up to 22,000 will drop coverage soon as policy rates keep increasing. Several insurance carriers have left Iowa’s market, making Minnesota-based Medica the only company to offer coverage across Iowa on the ACA exchange next year. The carrier has proposed increasing premium rates up to 56.7 percent amid uncertainty from the federal government about financing.

Iowa-based Wellmark Blue Cross & Blue Shield has indicated it would consider selling insurance in Iowa next year if the government approves the plan.

Just a handful of states have sought to change some funding rules for their individual ACA markets through the same waiver process Iowa is using, but data from the nonpartisan Kaiser Family Foundation shows Iowa’s plan is among the most expansive. Its approval could signal how receptive President Donald Trump’s administration will be to other state proposals.

If the federal government does give the green light, Iowa will have a short window to get its system up and running. Open enrollment for ACA health insurance coverage begins Nov. 1.

Ommen said his office has been preparing as if the federal government will give its approval.

“We need to move forward because if we don’t have a better option than what is being offered by the Affordable Care Act, we’re going to put Iowans through some really difficult times,” he said.