Now, parents, policy makers, and health providers are holding their breath as Republicans in Congress weigh potentially billions of dollars in cuts to Medicaid. Federal dollars pay for more than half of MassHealth’s $20 billion annual budget.

“MassHealth is a cornerstone for children’s health in Massachusetts,“ said Katherine Howitt, director of the Massachusetts Medicaid Policy Institute, an independent policy analysis program of the Blue Cross Blue Shield of Massachusetts Foundation.

The consequences of significant cuts to Medicaid, and the potential for voter outrage, have some doubtful Congress will ultimately cut from the public insurance program.

The information coming out of Washington is too vague to act upon, said Mike Levine, assistant secretary for MassHealth.

“We do not have specific contingency plans around what services we offer kids and what we might do if Congress or CMS takes actions we don’t like,” he said in an interview Monday.

Still, the possibility frightens Bernard. When her daughter, Victoria, was 2, before doctors had figured out what prescriptions and dosages would best control her epilepsy, she routinely had multiple seizures a week, her mother said. The child’s speech is delayed, but with the therapy MassHealth pays for, she is learning to express herself verbally.

“Without MassHealth I don’t know how I would do,” Bernard said. “I’m very concerned about it.”

Congressional Republicans have said they want to balance tax cuts by, in part, eliminating $880 billion in federal spending over 10 years. Leading Republicans, including President Trump, have said that won’t include cuts to Medicaid benefits. US House Speaker Mike Johnson has said his party is seeking only to reduce “fraud, waste, and abuse.”

But experts on health policy say there’s no way Republicans can achieve their budget goals without impacting Medicaid. At more than $600 billion a year, the program is among the federal government’s largest expenses.

“We know that the only way to achieve $880 billion in cuts is through catastrophic cuts to the Medicaid program as we know it,” said Megan Cole Brahim, a Boston University professor and co-director of the school’s Medicaid Policy Lab. “There’s really no way it wouldn’t have harmful implications for children.”

Massachusetts expanded MassHealth in 2006 to include children in households earning up to 300 percent of the federal poverty level, extending coverage to more children than in all but a few states.

As of 2023, only 0.6 percent of Massachusetts children were uninsured, according to a report from the state Center for Health Information and Analysis on insurance coverage in the state.

The state’s post-pandemic review of MassHealth eligibility led to about 363,000 people removed from membership last year, including almost 59,000 children ages 17 and younger, the state reported.

Even if Congress took a hatchet to Medicaid, Cole Brahim said she anticipated Massachusetts would seek to protect children from the brunt of the consequences. Officials could be forced to reduce access to some optional benefits, such as physical therapy, case management, and community health workers, and could reduce the kinds of prescription drugs, or the dosage amounts, covered by MassHealth.

Losing even partial Medicaid reimbursements would be devastating to community health centers and hospitals. On average, the health centers receive about 31 percent of their revenue from MassHealth, according to the Massachusetts League of Community Health Centers. MassHealth paid about 18 percent of all hospital revenue in the state as of 2022, according to the Blue Cross Blue Shield of Massachusetts Foundation. Boston Children’s Hospital reported roughly 46 percent of its Massachusetts patients are MassHealth members. Substantial cuts to Medicaid, hospital officials said, would create financial aftershocks that would affect every patient in the hospital.

“The danger for any children’s hospital in the country, [if] you start cutting Medicaid, you’re going to affect care delivery for every patient,” said Joshua Greenberg, Boston Children’s vice president of government relations.

On Monday, Governor Maura Healey and her partner, Joanna Lydgate, toured Children’s to highlight how potential cuts to Medicaid, as well as halts to millions in National Institutes of Health research grants, could affect patients. Kevin B. Churchwell, the hospital’s president and chief executive, said federal funding cuts have already disrupted clinical trials and research, including work with vaccines.

“We have patients in clinical trials who had their treatments stop because of this,” Healey said. “Can you imagine the cruelty of that?”

Among the groups Medicaid supports, including seniors and some people with disabilities, children are a relatively inexpensive clientele. They account for about 16 percent of the state’s total MassHealth expense. The families of some children enrolled also have private insurance but rely on MassHealth as secondary coverage to help with medical-related bills their insurer doesn’t cover.

For many children, MassHealth membership means more than covered doctor visits. The program pays whatever is needed to ensure children with disabilities have the equipment, care, and support they need. It allows children to receive Medicaid-covered services through their school’s health services and pays for behavioral health care in the community or home.

In addition, families on MassHealth get screenings to identify dental, aural, visual, or developmental concerns. Such wide-ranging and widely accessible insurance coverage can benefit children their whole lives. Children with good health care do better in school, a 2021 Blue Cross Blue Shield of Massachusetts Foundation report stated, and those with access to Medicaid tend to have fewer hospital stays, emergency room visits, and chronic conditions in adulthood.

Victoria Bernard’s doctor, Laura Livaditis, director of pediatrics at Mattapan Community Health Center, said about 90 percent of the children treated at the center are enrolled in MassHealth. Most of her patients are also from families living at or below the poverty line. MassHealth’s wide-ranging coverage has helped them to avoid evictions, she said. And for immigrants, the program has helped them make connections to ensure they have stable food and housing.

“I’m continuously impressed with the breadth and depth of services MassHealth covers for my patients,” Livaditis said. “I can’t remember the last time I had to fight with [MassHealth] insurance for needed services.”

Correspondent Emily Spatz contributed to this report.

Jason Laughlin can be reached at jason.laughlin@globe.com. Follow him @jasmlaughlin.