In pushing deep Medicaid cuts through Congress this year, President Trump and his Republican allies did not just squeeze a program that pays doctors and hospitals to provide poor people health care.

Over the last decade, states have increasingly used Medicaid dollars for another critical effort: helping the homeless and other vulnerable groups find stable housing.

To glimpse that little-known work, consider the journey of Michelle Cates, a food safety trainer who lost her job and apartment after a brain disease triggered seizures and intensified her struggles with anxiety and depression.

After two years in a Baltimore shelter, Ms. Cates received a federal rent subsidy. But finding an apartment was a challenge for a woman prone to blackouts and panic attacks.

A caseworker financed by Medicaid found a willing landlord and cut through the paperwork. Now she visits weekly to monitor Ms. Cates’s moods and medications, and even takes her to the grocery store, a crowded space Ms. Cates otherwise avoids for fear of passing out.

“This isn’t a battle I can fight alone,” said Ms. Cates, 44, as she worked a pair of crochet needles to calm her nerves. “If I didn’t have the help, I wouldn’t be here — I would be homeless again.”

The use of Medicaid to support housing, which requires federal approval, is mostly limited to services like case management. But a few states, including California, tap the health care program for security deposits and short-term rent.

The future of that work is in doubt. Mr. Trump’s signature domestic policy law, signed in July, is projected to reduce Medicaid spending by more than $900 billion over the next decade and push nearly eight million people off the rolls. While the law does not prohibit housing aid, the squeeze on state budgets could make such optional services harder to sustain, and analysts say that new work rules that go into effect in 2027 may disenroll the homeless at high rates, since many suffer from addiction or mental illness.

Proponents say that using Medicaid to house the homeless saves lives and money, arguing that people with housing are healthier and cheaper to treat.

Critics call the work a case of “mission creep” that diverts Medicaid from its core role of providing health care. Doubting the promised savings, they say housing aid inflates the program’s cost and threatens its financial sustainability.

“Housing isn’t health care,” Jackson Hammond, an analyst at the Paragon Health Institute, a conservative think tank, wrote recently.

While the first Trump administration approved several state requests to use Medicaid for housing services, the current administration appears more skeptical. Soon after taking office, a top official at the Centers for Medicare and Medicaid Services rescinded several documents issued under President Joseph R. Biden Jr. that encouraged the work.

The issue could come to a head next year, when California is required to seek federal permission to continue its housing work.

“Medicaid was not and is not intended to be a federal housing assistance program,” Kush Desai, a White House spokesman, wrote in an email, noting that other federal programs address homelessness. States that want to do more “are able to do so with their own funds,” he added.

Since some Medicaid cuts do not start until 2027, the impact on homelessness may take time to appear. But they already helped kill one program.

As the scale of the cuts became clear in June, North Carolina’s Republican legislature suddenly ended the Healthy Opportunities Pilots, a high-profile experiment that was midway through a five-year plan to spend $650 million on nonmedical services for Medicaid patients, including housing support. Legislators cited the cost.

In Baltimore, Health Care for the Homeless, a private clinic that receives federal funds, considers housing so central to health that it started a subsidiary to develop affordable apartments. But it was not until the first Trump administration let Maryland tap Medicaid that its housing casework found stable funding. Now the clinic provides housing support for 300 people like Ms. Cates.

Without the help, said Kevin Lindamood, the clinic’s chief executive, many would return to homelessness. “By helping people get and keep housing, we improved their health and reduced public costs,” he said. “These services save lives.”

About 30 states use Medicaid to support housing, though the scope of their efforts varies greatly. Maryland serves just 900 people. Before it suddenly ended, North Carolina’s program had served nearly 40,000. Housing aid grew in the wake of the Affordable Care Act, which added about 20 million people to Medicaid, including many who were homeless.

The homeless are expensive to treat. They have high rates of hospital readmission and rely heavily on expensive emergency room care. By helping them find and keep housing, the Maryland program, Assistance in Community Integration Services, or ACIS, seeks better care at lower costs.

One beneficiary, Robert Andrews, said his caseworker saved him from a relapse. Mr. Andrews, 58, who is recovering from a crack addiction, came to the program after 11 years in prison on drug charges and four years in a shelter awaiting a rent subsidy. When he told his caseworker where he planned to rent an apartment, she insisted he change plans.

“She said, ‘You’ll relapse in a day,’ and she was right — there were drug dealers right outside the door,” he said.

Now in stable housing for five years, Mr. Andrews, who suffers from schizophrenia, credits his current caseworker, Garrett Mosby, himself a recovering addict who was once homeless.

When he ran short of food, Mr. Mosby brought groceries. When the landlord ignored a plumbing complaint, Mr. Mosby brought a plunger. When he worries his children may never forgive him, Mr. Mosby, citing his experience, says healing takes time.

“Mr. Garrett’s like a father to me,” Mr. Andrews said.

If casework kept Mr. Andrews from drugs, it kept Christopher Green from eviction. A convenience store clerk, Mr. Green, 35, has raised three young children alone since his wife moved out six months ago. Though she left their public housing apartment, she would not remove her name from the lease, which doubled his rent and left him owing $1,400.

Worried about returning to living in his car, Mr. Green was immobilized. His caseworker, Shauna Griffin, persuaded the housing authority to accept a sworn statement saying his wife had left, which lowered his rent. Then she found a charity to pay his debt, preventing an eviction.

Without her help, “I would have lost this place,” Mr. Green said.

Renard Sandidge, 54, said housing had ended his trips to the emergency room. A survivor of childhood molestation who drank to manage the trauma, Mr. Sandidge found sobriety through a gospel mission and housing through an ACIS caseworker, who helped him use a voucher after landlords rejected his applications.

As a diabetic man living on the streets, Mr. Sandidge often neglected his medication, because he could not refrigerate it and because he was too depressed to care. He was hospitalized so often for diabetic ketoacidosis, a life-threatening condition, that a doctor asked if he was trying to kill himself. Since getting an apartment nearly three years ago, he has not been back.

“It’s a 100 percent turnaround,” he said.

More than three-quarters of the ACIS participants found stable housing, according to an evaluation by the Hilltop Institute at the University of Maryland, Baltimore County, and they were less likely than before the program to be hospitalized or to visit the emergency room. High-frequency users of emergency rooms fell by 30 percent.

But the local impact varied greatly, suggesting that outcomes may depend on housing markets or finding good caseworkers. The study did not address whether the program met its goal of reducing health care costs.

Critics say the housing work exceeds Medicaid’s proper boundaries, with California including services like mold reduction for people with asthma. While experimental services are supposed to pay for themselves by reducing federal health care costs — typically over five years — skeptics said that the upfront costs were certain and the long-term savings in doubt.

Adding services to a program that spends nearly $900 billion a year endangers Medicaid’s sustainability, said Mr. Hammond, the Paragon Health Institute analyst, who said states were using Medicaid “to create a backdoor entitlement to housing.”

Supporters of the work said that states were acting out of need. Federal housing aid reaches only one in four eligible people, while Medicaid’s financing lets it reach everyone who qualifies.

“If our housing programs were funded adequately, there would be no need to lean on Medicaid,” said Barbara DiPietro of the National Health Care for the Homeless Council, an advocacy group.

In Baltimore, Ms. Cates, the former food safety worker, has had housing for six months, an achievement that she said needs continued support. “Some days I’m OK, and some days I’m not,” she said.

She is used to uphill battles, beginning with a childhood of psychiatric hospitalizations and an attempt to end her life. Some doctors have suggested she has Asperger’s syndrome, a mild form of autism, which she said may explain why she has always felt socially disconnected. “I don’t do personal relationships,” she said.

Though she struggled, she worked: Ms. Cates supported herself for two decades, often with two jobs. And with a peak income of $60,000 she fell into homelessness from far above poverty. In addition to teaching food safety, she prepared taxes, styled hair, and worked in a funeral home and in hotels. “I like making money,” she said.

Medications helped her mood swings but left her numb, and she often stopped taking them, though panic attacks regularly followed. “I wanted to feel what other people feel,” she said.

As she approached 40, she began to have seizures. Unable to sustain steady work, she survived on savings, then moved to a shelter and suffered a stroke. Two years of shelter life “made me feel like total trash,” she said, but a housing voucher followed, with a caseworker to help her find an apartment.

Nationwide, more than 40 percent of people given vouchers fail to rent apartments in the allotted time, and Ms. Cates was so infirm that she had a seizure during the intake interview. Her caseworker, Deborah Woolford, sliced through a process notorious for red tape to get her a signed lease within several months.

When the rental office mistakenly thought Ms. Cates was behind in rent, Ms. Woolford fixed the error without telling her, to prevent a panic attack. “She might have run away and become homeless again,” Ms. Woolford said.

Though she receives disability payments, Ms. Cates is again applying for jobs.

One measure of her progress involves medical bills: Since getting an apartment, she has not returned to the emergency room, which she used to visit often.

Another involves pastels. For years, Ms. Cates had her bedroom painted black to reflect the darkness she felt. Now she sleeps in a pink cave, a bedroom adorned with her crocheted handiwork. There are pink pillowcases. Pink lampshades. Pink vines.

Soft, inviting, optimistic, pink is both an achievement and an aspiration — an expression of where she is and where she wants to be.

“I want it to be bright, hopeful — so I can feel inside what I see,” she said.