MNsure is considering whether to follow the federal government's lead in adopting a series of rule changes that health insurers believe will help the struggling market where individuals buy coverage.

Earlier this month, the Trump administration finalized a series of "market stabilization" rules meant to stop people from enrolling in coverage only after they learn of medical problems, driving up premium costs for others.

But consumer groups argue tighter rules could deter the young and healthy subscribers that are most needed to improve the risk pool in the Affordable Care Act (ACA) exchanges like MNsure. The most visible change would shorten open enrollment for 2018 coverage from three months to six weeks — a change that already was scheduled for 2019 but nonetheless worries ­consumer advocates.

While the rule changes will apply across most of the ­country, the federal government granted flexibility to about a dozen states like Minnesota that operate their own health insurance exchanges.

"We want our market to be stable here, but we also want consumers to have enough time to make this choice," said Allison O'Toole, the MNsure chief executive, in an interview last week. MNsure officials said they were getting feedback from insurers and consumer advocates last week as they decide what to do.

The rules apply to the individual market where self-employed people buy health insurance along with those who don't get coverage from their employer or the ­government.

Fewer than 5 percent of Minnesotans purchase individual policies, but the market has been the focus of public attention in recent years due to changes in the ACA.

The ultimate fate of the law remains unclear, with Republicans in Congress and President Donald Trump last week saying that their previously stalled effort to repeal and replace the ACA has new momentum.

The ACA eliminated preexisting condition exclusions that health insurers used to control costs but were widely unpopular.

Since the exclusions went away in 2014, many insurers have struggled with financial losses in the individual market and hiked premiums or dropped out of certain counties or states as a result.

There's growing concern that in 2018, many individual market consumers across the country won't have many health plan choices because of insurer exits. At the same time, there's also evidence that the individual market is beginning to stabilize in some places.

The federal Centers for Medicare and Medicaid ­Services (CMS) says the rules finalized this month will help the individual market by shortening the open enrollment period, reducing fraud and promoting continuous coverage. The changes "are necessary to increase patient choices and to lower premiums," said CMS Administrator Seema Verma in a statement.

Insurers applauded the rules, including more verification for when individuals obtain coverage via special enrollment periods that occur outside the general open enrollment period.

But a large trade group for health plans coupled its praise with a challenge for the Trump administration, calling for a commitment by the government to fund "cost-sharing reduction" payments to health plans that effectively lower out-of-pocket costs for subscribers.

ACA backers, meanwhile, are skeptical of the new rules.

"Shortening the open enrollment period means you're very likely to lose more of the procrastinators, who are much more likely to be healthy," said Andy Slavitt, a former UnitedHealth Group executive who was acting administrator of CMS during the Obama administration.

While MNsure has flexibility to implement a number of rule changes, Minnesota insurance agents and "navigators" who help people enroll in coverage have been focused on the potential change in the open enrollment calendar.

Before the new rule, open enrollment for 2018 coverage was scheduled to run from Nov. 1 through Jan. 31, just like the sign-up period for 2017 coverage.

Shortening the period to six weeks ending Dec. 15 would be a problem, insurance agents say, because it would concentrate the individual market business during roughly the same time period as open enrollment for Medicare health plans, which ends Dec. 7. November and December also is a busy time of year, agents say, for working with employer groups on coverage for the new year.

"A six-week period of time is absolutely not enough time for everybody to be able to do this," said Bob Stein, president of the Minnesota Association of Health Underwriters, a trade group for insurance agents.

The health law funded a new group of insurance counselors called navigators who help people enroll in Medicaid and MinnesotaCare coverage in addition to individual health plans. With a shorter open-enrollment period for the individual market, navigators would try to push some of the sign-up activity for public programs to other parts of the year, said Meghan Kimmel, president of St. Paul-based Portico Healthnet, which employs 13 navigators.

"We cannot keep up with the demand during open enrollment as it is," Kimmel said. "I have real concerns about our ability to meet our clients' needs with a shorter open-enrollment period."

The Minnesota Council of Health Plans, a trade group for insurers, says it wants to work with brokers and navigators to see if there's a way to make the shorter sign-up period work. Eagan-based Blue Cross and Blue Shield of Minnesota has endorsed changes.

"Ensuring individuals are enrolling for coverage on an annual basis for an entire plan year is a necessary step toward encouraging ­continuous coverage for at least an entire year and limiting the ability of individuals to wait to purchase coverage until the need for care arises," wrote Scott Keefer, Blue Cross' vice president for public affairs and communications, in a March 7 letter to federal officials.

Minneapolis-based UCare was supportive in a letter last month, while also suggesting that state-based exchanges like MNsure be allowed to extend the period by two weeks at the start of open enrollment. Minnetonka-based Medica said the change might "reduce administrative burden" on insurers. In a March letter, Medica requested that exchanges like MNsure "not be granted flexibility to lengthen the open enrollment period."

There's growing evidence that consumers have been gaming the system via the lengthy open-enrollment period and other lax rules within the ACA, argued Peter Nelson, a vice president with the Center of the American Experiment, a conservative think tank in Golden Valley. Tightening the enrollment period sends a message that people can't wait to buy coverage until they get sick, Nelson said.

"When you have a long open enrollment period that covers a substantial amount of the year, that just feeds into the notion — 'Oh, there's always going to be a way to get coverage,' " Nelson said. "I would encourage them to follow what the feds are doing."

But Lynn Blewett, a professor of health policy and management at the University of Minnesota, said she doesn't see evidence that the longer sign-up period lets many people delay getting coverage until they are sick.

There's also scant evidence, Blewett said, to back up the concern that a shorter open-enrollment period would exclude young and healthy people.

What seems likely, she added, is that consumers might be confused with a shorter enrollment period, since many have become accustomed to the three-month window.

"That's my concern — there won't be enough information and education of consumers," Blewett said.