WASHINGTON -- Ohio insurers want big premium hikes next year for individual health care policies in the Affordable Care Act market, with typical average increases of 20 percent or more.

Their rate requests have not yet been granted, but federal and state filings show the extent of the hikes insurers say they want -- and need -- because of expectations of costs for medical care, prescription drugs and the premiums necessary to cover these and other expenses. Insurers say they base their requests on how things went this year and last, and their projections for 2018.

These rate requests, and requests in other states, are likely to intensify public debate about Obamacare, at a time when Republicans in Congress have failed to repeal and replace it as they wished. Insurers and the Ohio Department of Insurance cautioned cleveland.com, which reviewed filings, that the rates are not final and could change. The state will continue reviewing premiums in coming weeks before sending its approval to Washington, where the U.S. Department of Health and Human Services, or HHS, will sign participation agreements with insurers in late September.

These rates also do not reflect the possibility that certain federal payments to insurers will end under President Donald Trump. The payments were built into the ACA as a way to hold down out-of-pocket costs for low-income buyers, and although Trump has threatened to stop them as a way he says could make the ACA crumble, a group of Democratic state attorneys general Tuesday won the right to keep up a legal challenge to prevent that.

Regardless, some if not all the Ohio insurers, including CareSource, Summa and Medical Mutual, submitted their requests for premium hikes with the expectation that they will get the federal cost-sharing payments. If they don't, they'd have to amend their requests and ask for even more money. "If these consumer benefits end, the current proposed rates would not be supportable and would need to be revised," said Fran Robinson, media relations manager for CareSource.

Some examples of average premium-hikes requests:

20.2 percent for Medical Mutual of Ohio individual policy buyers who use HMOs for their care. Medical Mutual coverage for point-of-service coverage that does not involve an HMO would rise by 36 percent.

17 percent to 28 percent premium hikes for Summa customers, depending on features of their plans.

29.28 percent for Buckeye Community Health plans, and slightly more on average for Buckeye plans that cover vision and dental care.

Not all premium requests go up as steeply. For example, while CareSource lists a 23.9 percent average hike, it also lists an HMO plan with premiums that would go up by 11.69 percent. Similarly, Canton-based AultCare lists an average hike of 11.45 percent.

But that's an exception to the trend.

The size of the hikes stand out on their own, but they also contrast sharply with relatively small increases for some insurers' small-group policies for businesses-- another component of the ACA.

For example, Medical Mutual requested hikes of only 3.2 percent for its small-group point of service plans, 4.27 percent for small-group HMO plans and even a premium cut averaging 2.47 percent savings in another small-group plan.

That stands in sharp contrast with the small-group rates of a smaller insurer, Northwest Ohio-based Paramount Insurance Company, which has requested small-group hikes ranging on average from 20.5 percent to 31.7 percent, HHS data show.

For most individuals and families who purchase their own health coverage, the steep hikes would be cushioned by ACA tax subsidies that about 80 percent of buyers get to offset their premium costs. For middle-class families who make too much to qualify, however, the hikes are likely to bolster complaints.

"These rate increase requests show once again, that Obamacare is broken and we need a long-term solution that lowers the cost of coverage and provides access to quality care, while protecting the most vulnerable in our society," Emily Benavides, spokeswoman for U.S. Sen. Rob Portman, said. Portman, an Ohio Republican, "will continue working with colleagues on both sides of the aisle to help Ohio families who are suffering under the failed status quo," Benavides said in an email.

So why do insurers want so much more?

In most cases, the answer is straightforward: Medical costs are likely to outstrip revenue if premiums don't rise.

"The amount of premium collected in 2016 was not sufficient to cover all of CareSource's claims and administrative expenses incurred by members in the plan during that time period," CareSource said in an explanation to HHS, which under the ACA requires early notice of any rate hikes exceeding 10 percent. "This imbalance in revenue versus expense to the plan makes up a portion of the 23.9 percent premium increase requested from 2017 to 2018."

But Molina Healthcare of Ohio says it made enough last year to cover its costs. The current political and market uncertainty, however, combined with projections of higher costs in 2018, justify its request, it told HHS.

"Although Molina's financial experience has met or exceeded expectations in the past, a premium increase is necessary to cover increased expenses expected in 2018," its filing said. "The uncertainty of the enforcement of the Individual Mandate, inclusion of the ACA Health Insurers Provider Fee, medical and prescription drug cost inflation, and incremental administrative costs to provide better service to our members contributed to the premium increase."

U.S. Sen. Sherrod Brown, an Ohio Democrat and booster of the ACA, said Trump and congressional Republicans have injected uncertainty into the market, and that's partly reflected in some premium-hike requests.

"The dangerous game the president and Washington politicians are playing has real consequences that are hurting working families in Ohio," Brown said in a statement. "They've already caused prices to rise. The threats and uncertainty need to stop. Instead, let's work together to lower costs and stabilize the market."

Until this week, it looked like withdrawals from the ACA market in 2018 could leave up to 20 Ohio counties without a single carrier. The insurers who announced their exits -- Anthem Blue Cross Blue Shield and Premier Health Plan -- cited uncertainty over the ACA and its government payments among their reasons.

It is not known what kind of premium hikes Anthem was considering before it decision. But Premier, a small insurer based in Dayton, filed paperwork with HHS showing it was considering a whopping 33.3 percent hike. And that was before even factoring in the possibility that it would need even more money if Trump pulled the plug on cost-sharing payments.

The Ohio Department of Insurance and five insurers announced this week that they will fill the void in 19 of those 20 counties.