State insurance regulators would also have to sign off. That, too, could be very complicated. Many states have enacted laws that require all health insurance policies to meet the standards in the Affordable Care Act starting Jan. 1.

Obama administration officials said states can choose whether to allow current health plans to be extended. And it’s up to the insurance companies whether they want to renew the policies.

Would consumers who have received cancellation notices be better off buying insurance through the new Obamacare online marketplaces?

It depends.

Some consumers would probably benefit from the law’s new protections. Some also probably will end up paying less, thanks to government subsidies.

But others would have to pay more for a health plan offered in the new marketplaces. Or they may have to select a plan with a network that does not include as many doctors or hospitals.

So, what effect will the administration's announcement have?

That’s unclear.

If many insurers are allowed by state regulators to renew existing policies and choose to do so, then fewer healthy Americans may join the new marketplaces created by the Affordable Care Act.

That could destabilize these marketplaces, which rely on healthy customers to keep insurance premiums in check. If there are not enough healthy consumers enrolled, premiums could soar in 2015.

Administration officials say they are confident that eventually more consumers will move into the marketplaces because the marketplaces will offer superior health coverage and because many consumers will qualify for government subsidies. These subsidies will not be available to people who renew their current plans.

But insurers and state regulators, concerned about destabilizing the marketplaces, are resistant to renewing canceled policies. In the end, very few of the consumers whose policies were canceled may actually be offered the opportunity to renew.

Follow Politics Now on Twitter and Facebook

noam.levey@latimes.com

Twitter: @noamlevey