Enrollment for health insurance under the Affordable Care Act soared in the final days before the federal sign-up deadline, bringing the total numbers to within a few percentage points of last year, when the enrollment window was twice as long.

In Texas, more than 550,000 people enrolled between Dec. 10 and Dec. 15, nearly doubling the total of enrollees over the previous six weeks combined, according to the federal Centers for Medicare and Medicaid Services, which released the figures Thursday.

A total of 1.13 million Texans signed up for insurance on the federal exchange during this year’s 45-day period, coming in 8 percent below last year’s total of about 1.23 million, when open enrollment lasted three months.

The numbers still could climb, because people affected by this year’s hurricanes have been given extra time to sign up. In addition, the numbers don’t include people who were in the process of enrolling before the deadline and had to leave call-back numbers because of high volume.

Nationally, total enrollment this year topped 8.8 million people, 4 percent below last year’s total of about 9.2 million during the longer enrollment window. More than 4.1 million people signed up in the final week this year, according to the Centers for Medicare and Medicaid Services.

"The fact that people still signed up, and really at a higher rate than in previous years, shows people want insurance and that (the Affordable Care Act) is their most viable way to get it," said Kay Ghahremani, chief executive of the Texas Association of Community Health Plans. "It is a testament to the fact that people want to have (health) insurance."

Open enrollment for 2018 insurance under the Affordable Care Act — commonly known as Obamacare — began Nov. 1 and ran through Dec. 15.

The figures released Thursday don’t include people signing up in states that operate their own exchanges and that in many cases have longer open enrollment windows.

Ghahremani, whose organization includes three insurers that offered health plans on the federal exchange this year, said all of them were surprised by the rates of enrollment they experienced — given the negative rhetoric regarding the Affordable Care Act from Republican lawmakers who repeatedly tried to kill it.

"They are not seeing a huge decrease in their enrollment from last year, when the enrollment period was double," she said. "So that seems to indicate that people are still very interested in getting health insurance."

In addition to shortening the enrollment period this year, the Trump administration cut money for an annual federal campaign to promote it by 90 percent — to $10 million — and reduced funding for health care navigators, organizations that educate people about their insurance choices and help them sign up.

Funding for Texas navigators was cut by 34 percent this year — to $6.1 million from $9.2 million last year — according to the Kaiser Family Foundation.

Larry Levitt, a senior vice president at the Kaiser Family Foundation, said in a social media post Thursday that the 8.8 million people who signed up nationally this year included 2.4 million new customers to the federal marketplace — including "one million new customers (who) signed up in the last six days alone."

The Centers for Medicare and Medicaid Services hasn’t released county-level sign-up data yet. But Austin health advocates have been reporting high rates of enrollment since the start of this year’s sign-up window, even while battling confusion among many potential enrollees regarding the fate of the law.

"The story line has been very negative (from the Trump administration), so many people may not even be looking at what their options are," Elizabeth Colvin, director of the Insure Central Texas program at Foundation Communities, said before the deadline expired last week. "We have heard that, and we have also heard confusion as to whether or not there will be a penalty" for people who don’t have health insurance in 2018.

The individual mandate that requires everyone to have insurance or pay a penalty remains in place for 2018. But the Republican-led tax bill that passed in Congress this week, which is expected to be signed by President Donald Trump, eliminates the penalty for 2019. When the mandate is no longer in place, some observers say opponents of the Affordable Care Act could finally accomplish their goal of killing the law.

"That will be the biggest destructive factor in the marketplace,"Ghahremani said. "Without other changes, that certainly will lead to the demise of the market. Insurance plans will increasingly have (only) the sickest individuals in their enrollment — and the dreaded death spiral will happen" of skyrocketing premiums or insurers dropping out of the marketplace.