WASHINGTON » Facing a record surge of Americans applying for health coverage on HealthCare.gov, the Obama administration moved late Tuesday to extend the deadline by 48 hours for enrolling in coverage for 2016.

Consumers in the 38 states that rely on the HealthCare.gov marketplace, which includes Hawaii, will now have until 9:59 p.m. Hawaii time Thursday to sign up for a health plan.

“Hundreds of thousands have already selected plans over the last two days and approximately 1 million consumers have left their contact information to hold their place in line,” said Kevin Counihan, who oversees the marketplace at the U.S. Department of Health and Human Services.

“Our goal is to provide access to affordable coverage, and the additional 48 hours will give consumers an opportunity to come back and complete their enrollment for Jan. 1 coverage.”

The move by the federal health agency came as several state-run marketplaces, including New York and Minnesota, also extended their deadlines.

In California, the nation’s largest state-run marketplace, officials also will extend the deadline until Dec. 17, according to Covered California Executive Director Peter V. Lee.

Demand was so high over the last several days that HHS, which operates the HealthCare.gov marketplace, had already been making some consumers wait several minutes before they could log in and select health plans.

Some who telephoned federal call centers were asked to leave their contact information so officials could call them back and complete their application after Tuesday’s deadline.

The federal call center handled nearly a million calls Monday, making it the biggest non-deadline day in the three years of the marketplace, according to the health agency.

Overall, the final days heading into the Tuesday deadline were the busiest HealthCare.gov had ever experienced, according to HHS.

The 2016 open-enrollment period — the third since marketplaces created by the Affordable Care Act began offering coverage in 2014 — is scheduled to run until the end of January.

But the original deadline had required consumers who wanted coverage to begin Jan. 1 to sign up by 3 a.m. Wednesday Eastern time.

Consumers who had started the process before the deadline but not completed it will still be able to go back, according to the health department.

The law allows Americans who don’t get health benefits at work to shop among plans on state-based marketplaces operated by the federal government or by the states themselves, including California, Connecticut and Maryland.

Consumers making less than four times the federal poverty level — about $47,000 for a single adult or $97,000 for a family of four — qualify for subsidies.

Insurers must provide a basic set of benefits and cannot turn away consumers, even if they are sick.

Staff writer Chad Terhune in Los Angeles contributed to this report.