AUGUSTA — Many states are gearing up to enroll more residents into Medicaid coverage starting in January. But thousands of Mainers are preparing to lose coverage this winter because of changes to the state’s program and the decision not to expand coverage under the federal health care overhaul.

More than 15,000 low-income parents are expected to lose Medicaid coverage in January when changes to the state’s Medicaid program kick in. An additional 10,500 adults with no dependent children and incomes less than $11,500 are facing the end of their coverage this winter even though they would have kept their coverage if the state had agreed to expand Medicaid.

Portland resident and U.S. Navy veteran Tom Ptacek is one of them.

Ptacek, 46, struggled to find work after serving in the Navy as a psychiatric technician. He worked the overnight shift at a gas station convenience store before leaving with the intention of finding a better job. But instead, he stumbled through rejection after rejection and eventually lost his home.

“What I didn’t realize was that I had gotten to a place emotionally where my tank was empty,” he said. “I just didn’t have anything left and … it took a couple weeks for me to build up the confidence to get out there and put applications in.”

After a year in a homeless shelter, Ptacek received housing through a grant from the Department of Veterans Affairs. He now makes $40 a week working as an advocate for the homeless.

The cuts to Medicaid, administered as MaineCare in the state, were meant to address several financial challenges facing the program when Republican Gov. Paul LePage took office, said Mary Mayhew, Commissioner of Maine’s Department of Health and Human Services. Several million dollars the state had been receiving from the federal government to support the program during the economic recovery dried up, she said.

“So we had to come in with a budget that looked across the board at eligibility, benefits and rates of reimbursement,” Mayhew said.

President Barack Obama’s Affordable Health Care Act lets states expand Medicaid to adults making up to 133 percent of the poverty level, or about $15,500 for an individual. The federal government offered to pay 100 percent of the costs for the expansion until 2016 when a portion of the costs would be shifted onto the state.

LePage vetoed the plan, calling it “welfare expansion” and saying the long-term costs of the program were unsustainable. The Democrat-led Legislature failed to get the two-thirds majority needed to override his veto.

The governor insisted that Maine shouldn’t expand coverage to more people because the state’s current system isn’t working properly. LePage and legislative Republicans point to 3,100 disabled Mainers who need home- and community-based service but can’t get funding for them under the current program.

But advocates say the loss of Medicaid coverage for low-income residents will be devastating and force them to seek care in emergency rooms at a much greater cost to the state.

More than 11,000 people were taken off the MaineCare rolls between February and May, according to the state Health Department. Many of the people who have and will lose their coverage will be eligible for federal subsidies to help them buy insurance on the new health care exchange beginning Oct. 1.

But 10,000 adults who lose MaineCare won’t be eligible for these subsidies, making it impossible for them to buy insurance, advocates say. The federal health care law assumes that states will expand coverage to people making about $15,000, leaving a group of low-income people ineligible for the subsides.

Mayhew said that issue needs to be addressed at the federal level.

“The federal government set the parameters for how you could expand,” she said. “It was an all-or-nothing question.”

But advocates say the issue is bigger than the 10,000 who are going to lose access to MaineCare. Christine Hastedt, public policy director for Maine Equal Justice Partners, said 25,000 childless adults are also on a waiting list for MaineCare coverage.

“That means there are a lot of people under the poverty level who need this coverage,” she said. “These 10,000 are going to lose coverage, but there are a lot of people …. under the poverty level who are not going to have access.”

Patty Kidder and her husband, Roger, were among those hoping that the state expanded Medicaid. The Kidders, both 54, are on the waiting list for MaineCare after losing their coverage last year. Since Roger lost his job in 2009, the couple has been living on the $11,000 Patty makes preparing people’s taxes out of their home.

Patty Kidder said her husband has frequent panic attacks that mimic heart attacks. But since losing their coverage, they’re hesitant to go to the hospital because they worry about racking up hospital bills.

“We have to second-guess whether these extreme panic attacks are a heart attack that is going to kill him or anxiety,” she said. “They tell you the quicker you get them to the hospital, the better their chance of survival and recovery. And yet, you’re sitting there wondering, ‘Do I go or do I stay? What do I do?'” she said.