WASHINGTON — Worried that insurers bailing out of the health law's markets may prompt their customers to drop out, too, the Obama administration plans to steer affected policyholders to remaining insurance companies. But those consumers could get an unwelcome surprise if their new government-recommended plan isn't what they're used to.

The backstop was outlined in an administration document circulating among insurers and state regulators. It also calls for reaching those “discontinued consumers” with a stream of reminders as the health law's 2017 sign-up season goes into full swing. Open enrollment for HealthCare.gov starts Nov. 1 and ends Jan. 31.

The health insurance markets were to facilitate private competition, but in many states they have run into problems that could lead to a greater government role.

Some consumer advocates say the administration's latest effort will help people hold on to coverage in a challenging year that will also see sharper premium increases. Insurers worry that government picking plans will sow confusion and may trigger a backlash from customers disappointed with reduced options. The administration says consumers have the last word as far as accepting any “alternate” plan they're offered.

“Many consumers are likely to be wary of information from another insurance company,” said Elizabeth Carpenter of the consulting firm Avalere Health. “Some individuals choose a plan based on a name they recognize or reputation. Other patients may also understand that things like benefit design and networks are likely to change, in some cases significantly, from one carrier to another.”

The Obama administration said it isn't able to provide an estimate of the number of people who'll get the notices, but independent experts say it could range from several hundred thousand to 1 million or more.

The market churn is due to a combination of big-name insurers leaving because of financial losses and the collapse of nonprofit insurance co-ops. Insurers say customers have turned out to be sicker than expected. Many younger, healthier people have stayed away, even at the risk of fines for being uninsured.