Final open enrollment numbers for the Obamacare federal marketplace were surprisingly strong, with 8.8 million customers selecting a plan by the sign-up deadline, officials said Thursday.'

In the final week of enrollment, 4.1 million people signed up on Healthcare.gov, with 1 million of those being new customers, according to snapshot figures published by the Center for Medicare and Medicaid Services on Thursday.

CMS said, however, that these figures are not final because they do not include those who signed up after midnight Friday, Eastern Time. These numbers also do not account for people who were in line to enroll and left their callback number.

The high level of demand came despite fears that an enrollment season cut in half and a sharp reduction in outreach budgets would depress the number of sign-ups. The sign-up season, the first full one under the Trump administration, ran from Nov. 1 through last Friday — but many customers were unaware of the deadline.

The number of people who enrolled in the plans sold on Healthcare.gov, the federal marketplace that serves 39 states, was just about 400,000 fewer than the number that signed up during the prior enrollment season.

@SeemaCMS: Exchange open enrollment for 2018 coverage ended w/ approx 8.8M people enrolling in coverage. Great job to the @CMSGov team for the work you did to make this the smoothest experience for consumers to date. We take pride in providing great customer service.

Lori Lodes, co-founder of the Get America Covered campaign, said these enrollment numbers are "huge." She said the sign-up totals from the final week of enrollment were "likely the biggest in the history of the marketplaces."

Lodes, who served as a top health care official in the Obama administration, said these figures are an "incredible indicator of just how much people want quality, affordable coverage."

"No wonder the administration scuttled their plans to release the enrollment numbers yesterday. Despite [President Donald] Trump declaring Obamacare dead just yesterday and all of his administration's efforts to undermine enrollment this year, we saw record demand and enrollments," she said.

Larry Levitt, senior vice president of special initiatives at the Kaiser Family Foundation, tweeted that he was "very surprised" that enrollment was only down slightly year over year.

"That didn't seem possible with a 90% reduction in outreach, an enrollment period cut in half, and a constant refrain that the program is dead," Levitt said on Twitter.

@larry_levitt: I confess to being very surprised that ACA marketplace enrollment is down only slightly. That didn't seem possible with a 90% reduction in outreach, an enrollment period cut in half, and a constant refrain that the program is dead.

There is now a chance that the final enrollment tally for all of the United States could match or exceed the 12.2 million people who signed up throughout the country in the last sign-up period.

Nine state-run Obamacare marketplaces are still selling individual health plans that take effect in 2018. Officials at a number of those exchanges have reported higher enrollment this season than last season.

Washington state's Obamacare marketplace said enrollment so far this year is 35 percent higher than the same time period last year. California's exchange, the nation's largest state-run marketplace, said sign-ups are 10 percent higher.

Also, people in a number of Healthcare.gov states — including all of Florida, Georgia, South Carolina and more than 50 counties in Texas — are still allowed to enroll in Obamacare plans because of a waiver given to those affected by hurricanes this year.

Charles Gaba, who runs the Obamacare tracking site ACASignups.net, said Wednesday that about 161 million people, or "almost precisely 50 percent of the total population" in the United States, live in areas with state-based Obamacare markets whose deadlines have yet to pass, or live in areas where they qualify for a special exemption that allows them to sign up for coverage through New Year's Eve.