Many Maine residents, even those with health insurance, struggle to afford their medical bills, a new statewide survey has found.

While the poorest Mainers reported the most difficulty affording health services, more than a quarter of residents with health coverage ran into trouble paying medical bills, according to the survey released Wednesday by the Maine Health Access Foundation.

Designed to track the impact of the Affordable Care Act in Maine, the survey polled nearly 1,000 residents in December 2013, just before new private policies purchased on Healthcare.gov took effect on Jan. 1, 2014. The research will provide a snapshot of the burden of health costs in Maine to serve as a benchmark in future years, said Dr. Wendy Wolf, president and CEO of the private nonprofit foundation.

“One of the most important questions that policymakers are going to want to know is what is happening in the wake of the Affordable Care Act with actually lowering the rate of uninsurance, and also helping people with the issue of both affordability and the types of benefits that are offered in insurance plans,” she said.

The foundation, which is leading the effort to sign Mainers up for health insurance under the ACA, partnered with market research firm GfK to conduct the survey. The poll piggybacked on a national health reform survey developed by the Urban Institute and funded by the Robert Wood Johnson Foundation and the Ford Foundation.

Bucking the national trend, Maine adults in the middle income range actually struggled more than their low-income counterparts to pay medical bills. About 35 percent of mid-range earners — with incomes between about $33,000 and $93,000 a year for a family of four — faced problems or were unable to afford their bills during the prior year, compared to 32 percent of those earning less. Many middle-income Mainers receive no government aid and don’t earn enough to buy a health policy with sufficient coverage, the survey results noted.

The Maine survey polled 992 adults between the ages of 18 and 64 across a range of incomes. Included were the uninsured; people who buy their own coverage in the individual market; those who get coverage through work; and Mainers with government-sponsored insurance, with the exception of Medicare.

The growth of bare bones, high-deductible health plans in the individual market likely contributed to many Mainers’ difficulty affording medical bills, Wolf said. Those plans will be phased out under the Affordable Care Act, except for those under age 30.

A chief goal of the law, also known as Obamacare, is to expand access to more robust and affordable health insurance, with free preventive care and a cap on out-of-pocket costs. Healthcare.gov, the federal government’s gateway for insurance marketplaces in Maine and 35 other states, targets private policies for individuals and small businesses, but also allows users to determine if they’re eligible for Medicaid.

In Maine, budget cuts led to thousands of residents dropping from Medicaid rolls as of Jan. 1. Gov. Paul LePage also opted out of expanding the low-income health insurance program, known as MaineCare, under the ACA. Earlier this month, the Maine Senate passed a bill to expand the program, but fell short of enough votes to overcome a veto from the governor.

Meanwhile, the state has emerged as a leader in signing residents up for coverage through Healthcare.gov, beating federal targets with more than 25,000 enrolled through March 1. About 90 percent qualified for federal financial help to afford their plans.

Wolf said she hopes Maine will enroll at least 30,000 residents through the federal marketplace by the end of the month. March 31 is the official deadline to enroll, though the Obama administration announced Tuesday that consumers can request an extension until mid-April.

“In Maine, we’re going to be in this interesting policy situation of expanding private coverage through the marketplace, but for lower-income people, having the coverage safety net pulled away from them,” Wolf said.

LePage has said expanding the program would impose a new burden on taxpayers, noting that health care expenses already consume a quarter of the state’s budget.

More than a third of uninsured Mainers in the survey reported foregoing medical care because they couldn’t afford it. Wolf said she expects that number to rise, particularly among those losing Medicaid coverage who don’t qualify for subsidized plans through Healthcare.gov.

The survey also showed people skipped dental care due to the cost, especially the poorest Mainers, but also nearly 11 percent of those earning four times the poverty level, or $94,200 for a family of four.

The survey will be conducted annually. The margin of error totaled plus or minus 3.1 percentage points.