WASHINGTON — Nearly 9 million people signed up for health insurance in the Affordable Care Act’s latest open enrollment period, despite the Trump administration having cut its duration in half.

The 8.8 million enrollees were only slightly fewer than the total in the last ACA open enrollment period, which, besides being longer, was much more heavily advertised. And millions more sign-ups were possible through state exchanges that are open until January 31, including those of California and New York.

Still, the future of the ACA was cast in doubt by the elimination of the individual mandate in the Republican tax overhaul. Without the mandate, people can go uninsured with no tax penalty. The change takes effect with the 2018 tax year.

Sen. Lindsey Graham (R., S.C.) tweeted “We have pulled one of the pillars of Obamacare out.” He said this year would bring another GOP effort to repeal and replace the law.

Senate majority leader Mitch McConnell of Kentucky had a different view, however, telling NPR, “Well, we obviously were unable to completely repeal and replace with a 52-48 Senate.” With the election of Sen. Doug Jones (D., Ala.), McConnell said, “We’ll have to take a look at what that looks like with a 51-49 Senate. But I think we’ll probably move on to other ­issues.”

Instead of overturning the law, he advocated bolstering the exchanges. “We want to steady the insurance markets if we can,” McConnell said, “and I think we’ll probably be addressing that part of health care” this year.