Now, they just just have to sign up another 8.65 million people.
More than 450,000 people selected Obamacare health insurance plans on HealthCare.gov in the first week of this year's open enrollment—and nearly half were new customers, federal officials said Wednesday.
Officials also said that 1,032,129 people submitted completed applications for eligibility for Obamacare plan coverage from Nov. 15 through last Friday.
Officials also announced new partnerships to help boost enrollment in the insurance plans in coming months.
"We're off to a solid start, but we've still got a lot of work to do every day between now and February 15," Health and Human Services Secretary Sylvia Mathews Burwell said, referring to the open-enrollment deadline. Burwell has set a goal of 9.1 million people to be signed up by the end of 2015 in Obamacare plans.
Burwell said that 48 percent of the 462,125 customers—221,820 people—who selected plans that go into effect in 2015 were buying insurance for the first time on HealthCare.gov, the federal Obamacare exchange that sells coverage in two-thirds of country.
The remaining 52 percent, or 240,305 people, were existing customers who had renewed coverage or replaced their current plans for 2015, Burwell said during a phone briefing with reporters.
For the selected plans to be considered official enrollments, people will need to pay their first month's premiums.
The number of sign-ups in just the first week is more than four times the 106,185 who selected Obamacare plans in the entire U.S. in the entire first month of open enrollment last year, when HealthCare.gov and several state-run exchanges were technological disasters.
The tally released Wednesday morning did not include customers of exchanges operated by 13 states and the District of Columbia.
But it did include existing customers of the previously state-run exchanges of Oregon and Nevada, who would be considered new enrollments on HealthCare.gov if they had signed up in the first week. Those states turned over enrollment functions to HealthCare.gov this year because of serious problems on their exchanges last season.
Officials did not break out the numbers of people who came from Oregon and Nevada in the plan selection tallies.
But Andy Slavitt, the principal deputy administrator for the federal Centers for Medicare and Medicaid Services, said, "I think it's safe to assume that [those states] wouldn't be a substantial part of those numbers."
Charles Gaba, a website developer whose Obamacare enrollment tracking and projection blog ACASignups.net has become a resource for health-care analysts and media, said that as of Tuesday night, state-run exchanges had reported about 68,000 sign-ups so far. Gaba said that tally represented a minimum of state-based exchange sign-ups—some states haven't disclosed that tally, and others have not been issuing regular updates.
Gaba said that based on current confirmed reports and the trends he is seeing, he projects there are now 890,000 people who have selected health plans across all government-run exchanges nationally.
"I'm extremely happy" about the sign-up levels reported by HealthCare.gov, Gaba said. "I think it's very good."
In addition to the sign-up data, officials said more than 3.7 million people visited HealthCare.gov online in the first week of operation.
Officials also said that 1,069,378 people phoned HealthCare.gov's call center in the first week.
Burwell said the numbers released Wednesday show that "people are ready to get covered, and visitors to HealthCare.gov are seeing more competition, affordable options and an improved consumer experience."
Kevin Counihan, CEO of HealthCare.gov, said during the call that HHS has entered into three new partnerships to further spur sign-ups.
The first is with giant mall operator Westfield Shopping Centers, whose sites will allow navigators and other assistors to provide information about Obamacare exchanges in some of its centers, where 425 million people visited last year.
HHS also is partnering in similar initiatives to get out the work about Obamacare with the National Community Pharmacist Association, which consists of 23,000 independent pharmacies, and the XO Group, a consumer Internet and medical company, Counihan said.
Wednesday's call was the first formal briefing about enrollment statistics this season.
Read MoreBurwell calls for transparency
Burwell said officials will be giving weekly "snapshots of preliminary data," something HHS refused to do last open enrollment season, in contrast to some state-run exchanges.
HHS also will be doing detailed monthly updates about enrollment figures nationally, which it did last season.
CNBC, in a story last weekend, had pointed out that HHS had not at that time released data on the first week of open enrollment, unlike some state exchanges.
Burwell on Sunday night sent senior staffers an email asking them to begin meetings to discuss how HHS can strengthen a "culture of increased transparency, ownership, and accountability" in the department.
Slavitt also said that in contrast to last year, HealthCare.gov is running relatively smoothly after less than two weeks of open enrollment.
"We believe that for the vast majority of users, they're having a faster, better, and more intuitive experience," he said.
He acknowledged some technical "bumps," which included returning customers being asked to reset their passwords, and two occasions in which customers were placed in an online "waiting room" due to high volumes of visitors. Slavitt said that while more bumps were likely to occur in the future, he was confident that HealthCare.gov's tech staff would be able to quickly resolve problems.
Slavitt said HealthCare.gov so far this season has had, at most, 55,000 users online at a given time. The site is designed to handle 250,000 customers at once, he said.
A month before the start of open enrollment, there were about 6.7 million people enrolled in Obamacare health plans sold through both HealthCare.gov and the state-run exchanges.
Last week, HHS admitted it had in September, and at the beginning of November, incorrectly claimed that total enrollment was above 7 million.
HHS said that it twice mistakenly double-counted enrollees who also had separate dental plans, which inflated the tallies.
HHS said last week: "Our target for 2015 open enrollment remains 9.1 million individuals. Moving forward only individuals with medical coverage will be included in our effectuated enrollment numbers."
Burwell was asked Wednesday by a reporter if the sign-up tally she was releasing including dental plan enrollees.
"They are not included," she answered.
Read MoreCat got your tongue, HealthCare.gov?
Burwell said she has asked Slavitt to investigate why the dental plan customers were previously included.
Earlier this year, the Congressional Budget Office projected 13 million people would be enrolled in Obamacare by the end of 2015. HHS recently said it had a lower projection due to new analyses and data from other government-run health programs such as Medicare and Medicaid.
Burwell was asked Wednesday if the current sign-up rate has lead her to change the 9.1 million enrollment projection.
"We are keeping our goal," she said. "We are staying with that number."
"It's still early, and we have a long way to go, but we're off to a solid start," Burwell said.
Most of the existing customers on HealthCare.gov, as well as many existing customers on some state-run exchanges, will be automatically re-enrolled in their plans if they take no action by Dec. 15.
Burwell encouraged all current customers to visit HealthCare.gov and renew their options, particularly since new insurers have entered the exchanges, potentially offering better deals than the ones some people have.
Ceci Connolly, managing director of PricewatehouseCoopers' Health Research Institute, said the numbers released Wednesday are encouraging.
"This looks to be a solid start thankfully without the technical problems that plagued last year's open enrollment," Connolly said. "The question is whether people re-enrolling are hunting for the plan and price that best suits their needs. If they don't shop around they may be disappointed."
Correction: This version corrected the spelling of the second name of Sylvia Mathews Burwell.