WASHINGTON – Even while hailing an estimate that 1 million more people are getting insurance coverage through Obamacare, Health and Human Services Secretary Sylvia Burwell acknowledged that “substantial” reforms are still needed in the nation’s health care system.

But one idea she highlighted Wednesday is being attacked by Republicans, even some Democrats, and insurers who say it would lead to more government involvement in health care.

Burrell, as well as Democratic presidential nominee Hillary Clinton, would create public insurance plans to compete with private insurers on the Affordable Care Act’s health insurance exchanges.

The idea is give people a cheaper option, particularly in about one-third of the nation’s counties — many rural — where residents can only go to one insurer to get coverage on Obamacare’s state exchange.

Higher-than-expected costs for insurers are driving up premiums — in some cases by almost double.

Some companies, such as Aetna and UnitedHealth, have pulled out of the exchanges in some areas.

As a result, one-in-five people insured through the exchanges will now have only one option for coverage, according to a study by the Kaiser Family Foundation in August. That included 41 percent of people living in rural areas.

Five entire states — Oklahoma, Alabama, Alaska, South Carolina and Wyoming — were expected to have just one insurer offering coverage on the exchange as of the open enrollment period that begins Nov. 1, the study found.

In a number of other states, there is scarcely more choice for customers.

Two insurers offer plans on the exchange in West Virginia, and 82 percent of its counties are expected to have only one insurance provider, according to the study.

“In rural places, where you don’t have a lot of providers, the question is how do we make sure people have coverage and how do we make there there is competition?” Burwell said while speaking with correspondents for regional newspapers in Washington, D.C. “We think (a public option) is a very good solution to that.”

President Barack Obama has backed the idea, as has Clinton. Republicans, who’ve made a campaign issue of rising insurance costs associated with the Affordable Care Act, have sharply criticized its expansion. 

Offering a public plan, alone, will not address factors driving up insurance premiums, said Cynthia Cox, associate director of Kaiser’s health reform research.

More sick people signed up for insurance than insurance companies expected when setting premiums last year, she said. Insurers are now raising rates to compensate.

Cox said the market adjustment should be temporary, and rates should stabilize.

In July, a separate Kaiser study found that premiums for the lowest-cost plans in the health exchanges could increase by 9 percent, after rising 2 percent the year before.

Rates are skyrocketing in some areas, though. Blue Cross Blue Shield of Oklahoma – the only insurer offering plans in that state’s exchange – intends to raise rates from 58 percent to 96 percent. Oklahoma Insurance Commissioner John Doak called the increases “jaw-dropping.”

Many people, however, will not actually pay higher premiums because they qualify for subsidies and pay only a set amount for coverage.

The increases do hurt those who buy insurance through an exchange but make too much to qualify for subsidies.

A government insurance plan could offer cheaper premiums by paying doctors and hospitals less money than private insurers – just as Medicaid and Medicare do, according to a 2013 Congressional Budget Office study.

The public plan’s lower rates could push private insurers to pull out of some exchanges.

On the other hand, a public plan’s lower reimbursements could cut costs for private insurers, as well, leading them to lower their rates, too, Cox said.

Health care industry groups warn that some doctors may not participate in a public plan, or will cut back services because they won’t be paid as much. That could leave patients with poorer quality treatment and fewer choices for doctors.

“We need to solve problems, not make them worse,” said Marilyn Tavenner, president of America’s Health Insurance Plans, a trade association, in a statement.

Tavenner and other critics, including the American Hospital Association, called for other changes to Obamacare before a government plan is created, such as preventing people from signing up for coverage then dropping it after getting treatment.

“If we have learned one thing from Obamacare, it’s that government-run health care leads to higher costs, lower quality, and fewer choices for Americans. … We need less bureaucracy in our healthcare system, not more,” said House Ways and Means Committee Chairman Kevin Brady, R-Texas, in a statement this summer.

Burwell, meanwhile, defended Obama’s health care reforms, as the administration enters its final couple of months.

“Have we had challenges? Sure. This is a complicated thing. We’ve been trying to do this for 100 years,” she sad.

Still, she noted 8.6 percent of Americans do not have health insurance — the lowest portion in the country’s history.

Limits on out-of-pocket costs mean those with serious illnesses aren’t going to “get to the point where you’re going bankrupt,” she said.

The end of annual or lifetime limits on coverage has also helped, she said, recalling a woman who delayed getting chemotherapy because she ran out of coverage.

Republicans, though, have said they will change the program while keeping its safeguards.

Brady’s statement pooh-poohed the projections about insuring 1 million more people and raised doubt about Obamacare’s success.

“The administration’s glowing predictions pale in comparison to the millions of Americans who have been kicked off of their health care plan, cannot afford their monthly premiums, and cannot visit the doctor they’ve seen for years,” he said. “The American people deserve a health care system that actually meets their expectations.”

Kery Murakami is the Washington, D.C. reporter for CNHI’s newspapers and websites. Contact him at kmurakami@cnhi.com.