The House Republicans unveiled legislation last week to replace the Affordable Care Act, and the bill’s various proposals—such as rolling back the expansion of Medicaid—have local health care officials considering the worst possible outcomes.

Medicaid, which in California is called Medi-Cal, covers over 12 million people in the state, a third of whom were added following the program’s expansion from 2014 to 2016. In West Marin, the Coastal Health Alliance sees over 1,500 adults and children covered by Medi-Cal. The recent expansion brought 150 new Medi-Cal patients to the Bolinas clinic and 641 to the Point Reyes Station clinic. Steven Siegel, the nonprofit health center’s C.E.O., said that changes in the Medicaid system could have a considerable effect on patient access and revenues.

“About 750 West Marin lives will have more barriers in access to health care,” he said. “We’re waiting to see what changes will happen, and strategizing how to respond and maintain health services. The A.C.A. is a rational, but imperfect, attempt to address a broken health care system. So far, the replacement suggestions do not have that focus.”

During a town hall meeting on health care that was held  at the Marin Veterans’ Memorial Auditorium in San Rafael on Monday, Congressman Jared Huffman was beginning to explain how health care in rural areas has benefited from the A.C.A. when news broke that the non-partisan Congressional Budget Office had released its report on the proposed legislation. 

The office projected that by 2026, the number of people without health insurance would increase by 24 million under the Republican plan. Meanwhile, $337 billion would be shaved off the federal deficit.

“Just get ready,” Rep. Huffman said, telling his constituents that there would be an immediate reaction from the Republicans to discredit the C.B.O.’s report. 

Dubbed the American Health Care Act, the new bill seeks to repeal fundamental aspects of the A.C.A. Key changes include eliminating the individual mandate that penalizes people who do not have health insurance, changing the way tax credits are distributed by using age instead of income, and scaling back the expansion of
Medicaid. 

After the A.C.A. went into effect, over 30 states expanded their Medicaid programs—which provide health care for low-income people—by raising the income eligibility cutoff to include more people. California now receives $18 billion for Medi-Cal from the federal
government. 

The proposed legislation would continue federal funding to state Medicaid programs until 2020, but would then reduce it. The bill proposes a cap on federal funding per enrollee based on how much the state was spending in 2016.

According to Ken Jacobs, chair of the University of California, Berkeley Center for Labor Research and Education who presented at the meeting, 14,000 Marin residents were enrolled in the Medicaid expansion. If the Republican bill were to pass, the expansions would begin to phase down in 2020, “[forcing] the state to make very difficult choices.” 

Mr. Jacobs also described the effects the new bill’s tax credit system could have on different age groups. According to the Kaiser Family Foundation, a non-partisan organization focused on health care, a Marin resident who is 60 years old and has an income of $40,000 a year would stand to lose over half of his or her tax credit in 2020 under the proposed bill. 

Another panelist at the town hall meeting, Grant Colfax, director of Marin County Health and Human Services, said 50,000 Marin seniors—or one in five Marin residents—are at risk of losing health care under the plan.

“Older Americans with low or modest incomes and poor people on Medicaid would suffer the most,” he said. “This bill is transformative in a negative way; it’s Medicaid rationing. The reduction in Medicaid is one of the more egregious parts of this bill.”

He added that the county was “really making progress in building [health care services] in West Marin” and that the A.C.A. supports over 600 jobs countywide. 

The Coastal Health Alliance, which employs around 50 people, could see job losses if the repeal passes, Mr. Siegel said. 

In addition, the alliance’s mobile dental van program is largely funded through Denti-Cal, a part of the Medi-Cal program. As a newer—and costly—program, Denti-Cal could be one of the first programs to be cut, Mr. Siegel said.