President Barack Obama said on Friday more than half a million Americans enrolled in health insurance plans under Obamacare using the HealthCare.gov website during the first three weeks of December.
(Read more: Missing million: Obamacare's direct-enrollment flop)
"More than half a million Americans have enrolled through HealthCare.gov in the first 3 weeks of December alone," President Obama said in his final press conference of 2013. "Millions of Americans are now poised to be covered by quality, affordable health insurance come New Year's Day."
That brings the total enrollments through state and federal marketplaces to more than 1 million people to date, based on rough estimates of updated state and federal data, senior administration officials said.
Obama said that last-minute exemptions from the law announced on Thursday provided an additional safety net for a small group of people, and said he took the blame for the poor rollout of his signature policy achievement.
"When it came to the the health care roll-out, even though I was meeting every other week with folks and emphasizing how important it was that consumers have a good and easy experience in getting the information they need," he said. "The fact is, it didn't happen in the first six weeks and since I'm in charge, we screwed it up."
Timothy Jost, a health-care law expert and professor at the Washington and Lee School of Law, called the enrollment numbers announced by Obama "a start."
"I expect this will be par for the course from now through the end of March," Jost said, referring to the end of the open-enrollment period for Obamacare policies.
Touting recent improvements in the economy, Obama said 2014 could be a "breakthrough year" for the U.S.
The economic news, while modest, has been a glimmer of light for Obama in an otherwise difficult year.
Obama also voiced support for proposed legislation that would extend unemployment benefits by three months. The benefits expire later this month for about 1.3 million Americans.
Meanwhile, Obama stressed that he will not negotiate with Congress over raising the debt ceiling.
"It is not something that is a negotiating tool. It's not leverage,'' he said, adding that he does not expect a stand-off over the issue. "I've got to assume folks aren't crazy enough to start that all over again."
(Read more: After budget approval, more 'kumbaya' for DC?)
Obama is scheduled to leave Washington for Hawaii for the holidays. Friday's press conference marks the President's 44th solo press conference.
—By Reuters. CNBC.com and AP contributed to this report.