Mainers are signing up for Affordable Care Act marketplace insurance in record numbers, even as the law is under threat of repeal by a Republican-controlled Congress and President-elect Donald Trump.

Enrollments in Maine are 9 percent ahead of the same time period last year, according to numbers released last week by the U.S. Department of Health and Human Services.

Republican leaders in Washington have promised to repeal President Obama’s signature health care law shortly after Trump assumes office Jan. 20 and to devise a replacement within three years.

But some Republicans, including U.S. Sen. Susan Collins of Maine, have questioned whether the law should be repealed without a suitable replacement in hand that covers a similar number of people. About 75,000 Maine residents signed up for Affordable Care Act insurance in 2016, and most receive a subsidy to help pay for premiums. Collins has said she doesn’t want a repeal to take away insurance from thousands of Mainers.

Lisa Mae Parker, 55, of Parsonsfield said she has ACA insurance and would be upset to see it go away. Parker said she started a home-based baking business in part because she could purchase the insurance, have it cover a number of health services and not be too expensive. She said she pays about $314 per month and has a $2,200 deductible.

“I’m very, very nervous that Congress is going to be cavalier about repealing this law and we’re going to end up with a big mess,” Parker said.

Health insurance experts have said that if a repeal is approved without a replacement plan in place, insurers could flee the marketplace because of the uncertainty that would create in the markets. Insurers could exit the individual marketplace to avoid risking financial losses, causing a collapse.

In the meantime, enrollments are ahead of last year.

Emily Brostek, executive director of Consumers for Affordable Health Care, an Augusta-based advocacy group, said the demand for coverage remains strong despite the possibility that the ACA could be repealed.

“When you look at the surge in enrollments, it’s clear there’s a large number of people who want and need coverage,” Brostek said. She said perhaps many people are signing up to get their free preventative services while they’re still available, such as IUDs, mammograms, colonoscopies and flu shots.

Ashley McCarthy of Western Maine Community Action, which helps people sign up for marketplace insurance, said her agency is “booked solid” up to the Jan. 31 deadline for helping people enroll.

Nationwide, about 6.4 million people have enrolled in ACA insurance for 2017, beating last year’s numbers by 400,000. That does not include automatic re-enrollments. Of the 6.4 million, about 2 million are new customers, according to federal data.

In Maine, 56,270 had signed up for ACA insurance by Dec. 19. There are no state data on how many are new enrollees, but if Maine hews to the national trend, there would be about 17,500. If trends hold true, by the time the final numbers are counted after the Jan. 31 sign-up deadline passes, Maine will surpass the 75,000 enrollees in 2016 by about 10 percent.

Barbara Leonard, president and CEO of the Maine Health Access Foundation, which advocates for affordable access to health care, said the ACA is “still the law of the land.” But she said there’s a lot of uncertainty about what’s going to happen.

“Every day it seems there’s a new set of ‘ifs,’ ” Leonard said. “The health care and insurance industry represents about 20 percent of the entire economy of the United States. They should be thinking very carefully before they take the ACA apart.”

One of those new enrollees is Michaela McVetty of Portland, who opened Sisters Gourmet Deli in Monument Square last spring.

McVetty, 26, said she just migrated from being on her parents’ health care plan, and she’s feeling the financial squeeze of the monthly payments. She said she pays $140 a month for a plan with a $6,000 deductible.

“It’s not an enjoyable thing,” McVetty said. She said it’s another expense to deal with on top of all of the other expenses of opening a new business.

McVetty said she realizes the insurance could protect her from financial ruin if she were to ever have catastrophic health problems or experience a severe accident, but it’s still difficult to pay a lot of money for something that she probably won’t use much because she’s young and healthy.

But McVetty said she realizes that insurance has different values depending on who’s buying it, such as parents with children or someone who has a chronic disease.

“I don’t know what it means for the guy down the street or the girl who works for me,” she said. “I’m not hoping (the ACA) gets repealed.”