The Congressional Budget Office, which has estimated the law’s impact on U.S. health insurance coverage, expects about 13 million people to be enrolled in private plans sold through government-run insurance exchanges next year. The Obama administration distanced itself from that projection in November, saying the law’s programs would take longer than the budget office expected to ramp up and that employers haven’t eliminated workers’ health benefits in the numbers once anticipated, which would have moved more people to the government’s marketplace.

Promotional Campaign

Advocates for the law are mounting a promotional effort this weekend, ahead of the Dec. 15 deadline. People who don’t sign up by then can’t get coverage effective before Feb. 1. Customers already enrolled in Affordable Care Act plans will be automatically renewed in their current coverage after Dec. 15. Federal officials have encouraged current customers to shop around instead, out of concern that people who automatically renew may see unexpected premium increases in January.

Even that problem may be less of a headache for the government than expected: Pearson said about 16 percent of current Affordable Care Act customers had already returned to healthcare.gov to shop around before renewing their coverage, more than she or Levitt expected.

“I really expected very few people to come on the site and renew,” Levitt said in a phone interview. “So far it’s hundreds of thousands of people.”

Checking Coverage

That puts the government on pace to draw as many as 70 percent of current customers back to government enrollment systems to check their coverage before sign-ups end Feb. 15, Pearson said. Federal officials have said most people can save money by switching from their current plan to a lower-cost one with similar benefits.

“If you get anywhere near 50 percent of people actively renewing I will be stunned,” Pearson said. “Despite the fact that exchange enrollees are very price sensitive, there’s tremendous inertia when shopping for health insurance. No one likes to shop; everyone wants to just stay in the plan they picked last year.”

Raising Attention

The Health and Human Services Secretary, Sylvia Mathews Burwell, will travel to Arizona and Texas Dec. 13-14 -- states with large uninsured populations -- to promote enrollment. Her department wants churches to participate in a “Faith Weekend of Action” and encourage their members to sign up before the deadline. Healthcare.gov, meanwhile, sent an e-mail Dec. 10 to millions of people with accounts on the system, warning them that four days remain to enroll in a plan beginning Jan. 1.