CHICAGO - Anticipating heavy traffic on the government's health care website, the Obama administration effectively extended Monday's deadline for signing up for insurance by a day, giving Americans in 36 states more time to select a plan.
The grace period -- which runs through Tuesday -- was the latest in a series of pushed-back deadlines and delays that have marked the rollout of the health care law.
But federal officials urged buyers not to procrastinate.
"You should not wait until tomorrow. If you are aiming to get coverage Jan. 1, you should try to sign up today," said Julie Bataille, a spokeswoman for the federal agency in charge of the overhaul.
Bataille said the grace period was being offered to accommodate people from different time zones and to deal with any technical problems that might result from a last-minute rush of applicants.
The HealthCare.gov site had a disastrous, glitch-prone debut in October, but the government reported on Twitter that it was running smoothly Monday morning. It had no immediate estimates of how many people visited the site.
Monday had been the deadline for Americans in the 36 states served by the federal website to sign up if they wanted coverage upon the start of the new year. The remaining states operate their own online marketplaces, and some of them have also extended their deadlines slightly.
The extra day will add incrementally to the already daunting administrative problems for insurance companies, such as inaccuracies on applications, said health care industry consultant Robert Laszewski.
"Insurers would like to have two to three weeks to process applications. Now they're going to have a week, less one more day," he said. "When the day is done, it doesn't help."
President Barack Obama himself signed up for health insurance through the Washington marketplace over the weekend -- a purely symbolic move since he will continue to get health care through the military as commander in chief.
The White House said he enrolled to show support for the marketplaces, and he chose a less-expensive "bronze" plan.
Obama said on Friday that more than 1 million Americans had enrolled for coverage since Oct. 1. The administration's estimates call for 3.3 million to sign up by Dec. 31, and the target is 7 million by the end of March.
After that, people who fail to buy coverage can face tax penalties.
The government's original deadline already had been pushed back a week because of the technical problems that plagued the website, but hundreds of upgrades to storage capacity and software have cut error rates and wait times.
As the Monday deadline drew new, last-minute health insurance shoppers called help lines and attended enrollment events. More than 1 million people visited the website over the weekend, and a federal call center received more than 200,000 calls.
"It's just nonstop now. Everybody knows about it. Everybody wants it," said Florida enrollment counselor Madeleine Siegal. She said her organization in Fort Lauderdale was slammed with walk-ins and appointments Friday, had several weekend enrollment events and opened its doors an hour early on Monday.
Roger Colyn, 60, of Des Moines, Iowa, was happy when he left his Monday morning appointment with a state enrollment navigator. She helped him sign up for a "silver" plan that will cost him $10.79 in monthly premiums after government aid is factored in.
"I feel relieved," Colyn said.
Others said they will let the date pass without making a decision.
"I'm in no hurry, though it'd be nice to be able to visit a doctor without stress," said Kyle Eichenberger, an uninsured 34-year-old from Oak Park, Ill., who said he hit a wall on the website when he first tried to enroll early on.
"I'm an Obamacare supporter, though I think it is full of problems," Eichenberger said. "I'd like to see the whole system streamlined to be more user-friendly. Keep the basic idea, but don't make me feel like I'm navigating a maze to get a simple checkup."
Minnesota, one of the states running their own insurance exchanges, also had a Monday deadline. But amid problems with its website and extra-long hold times to reach its help center, it extended the cutoff date eight days, through Dec. 31.
Maryland has also extended its deadline, to Dec. 27.
Associated Press writers Catherine Lucey in Des Moines, Kelli Kennedy in Fort Lauderdale, Fla., Patrick Condon in St. Paul, Minn., Brian Witte in Annapolis, Md., and Donna Blankinship in Seattle contributed to this report.