The Obama administration provided its first major update on 2015 Obamacare enrollment. (AP Photo/David J. Phillip

At least 7.1 million people so far have enrolled in 2015 health plans through Obamacare's insurance marketplaces, according to a pair of federal reports issued Tuesday.

As of Dec. 26, 6.5 million people signed up for coverage in federally run exchanges — that includes new enrollments, people actively re-enrolling and existing customers who allowed their coverage to automatically renew, according to the Department of Health and Human Services' weekly enrollment update.

A second HHS report, which provides the most comprehensive look at the new enrollment period so far, found that 633,000 people selected coverage in the 14 states running their own health insurance marketplaces as of Dec. 15. That's in addition to those who signed up through the federal exchanges, for a total of roughly 7.1 million.

However, HHS said most states haven't reported complete information about the number of re-enrollments, meaning the actual enrollment count is likely higher.

About 3.4 million people had actively selected an exchange plan in the 37 states relying on HealthCare.gov enrollment platform as of Dec. 15, the federal deadline to sign up for coverage starting Jan. 1. About 87 percent of those people qualified for premiums subsides, and about 52 percent were purchasing coverage through the federal-run marketplaces for the first time this year. The remaining 48 percent were returning customers who either selected a new plan or actively re-enrolled in existing coverage.

By comparison, just 106,000 people had selected exchange health plans in the first month of enrollment last year, when severe technology flaws threatened the launch of the law's coverage expansion. This current enrollment period has run much more smoothly, though some customers are still experiencing problems on a smaller scale.

HHS has been providing weekly enrollment snapshots over the past month, but Tuesday's monthly report provided the most detailed breakdown to date of who's signing up for exchange coverage in the second year of the Affordable Care Act's coverage expansion, with another major Supreme Court decision on the health-care law looming in 2015.

Of the 3.4 million people selecting health plans through the federal enrollment Web site, 24 percent were between 18 and 34 years old, while 30 percent were between 55 and 64 years old. The young adult enrollment rate was up just slightly from 23 percent compared to the first three months of last year's enrollment season, HHS said.

More than two-thirds (68 percent) of federal exchange enrollees have so far selected "silver" health plans, which cover 70 percent of medical expenses. About 8 percent of enrollees identified of as Latino, which is slightly up from 7 percent reported during the first three months of last year's enrollment period. Eleven percent of enrollees identified themselves as African-American, down from 14 percent during the same period last year.

Of the 37 states using the HealthCare.gov enrollment platform, Mississippi had the highest percentage of new customers (58 percent) choosing 2015 health plans, while Alaska, Maine and North Dakota shared the lowest (39 percent). About 673,000 people have already signed up for 2015 coverage in Florida, the most of any state.

The administration seems likely to hit its own goal of enrolling 9.1 million people in 2015. That's significantly lower than the 13 million originally projected by the nonpartisan Congressional Budget Office.

The enrollment period is scheduled to end Feb. 15, just a few weeks before the Supreme Court will hear oral arguments on a lawsuit challenging the legality of subsidies provided through the federal-run exchanges. If the Supreme Court accepts ACA opponents' argument that the law only authorizes subsidies in states that set up their own exchanges, that would invalidate financial assistance to millions of enrollees in states relying on HealthCare.gov.

Despite the lawsuit's high stakes, HHS Secretary Sylvia Mathews Burwell last week wouldn't say whether her department is preparing contingency plans in the event the administration loses the Supreme Court case, King v. Burwell. A decision is expected in June.

"The idea that Congress intended for people of New York to receive these benefits for affordable care but not necessarily the people of Florida — we believe we have the right position," Burwell said.