ST. PAUL — A record number of residents signed up for private insurance this year through Minnesota’s health exchange, officials said Thursday, attributing the spike in part to uncertainty over the federal health care law and a novel state program that offsets skyrocketing premiums.

MNsure, the health exchange Minnesota created through the federal Affordable Care Act, signed up more than 117,000 people during the three-month open enrollment period for 2017 that ended Jan. 31. MNsure extended a special, one-week enrollment window that closed Wednesday night.

Sign-ups on the individual market, where shoppers who don’t already have coverage through employees or government programs can buy it, were up by more than a third from last year, exchange chief executive Allison O’Toole said.

At both the state and federal level, health insurance exchanges like MNsure have a cloudy future. President Donald Trump has vowed to replace the Obama-era health care law, and Republicans who control Minnesota’s Legislature have indicated they’ll move to abolish MNsure in the meantime.

Combined with concern about shrinking plan access in Minnesota’s fragile health insurance market, O’Toole said that uncertainty might have prompted more Minnesota residents to try to lock in coverage before there are massive changes.

“They wanted to make sure that they got covered, and they did,” she said.

Minnesota provides a contrast for the rest of the nation, which saw an overall decrease in health plan sign-ups in the open enrollment period that ended Jan. 31.