The future of the nation’s disability services is on the line, advocates say, as Congress reconvenes to consider legislation that could chop billions from Medicaid.

Earlier this month, the U.S. Senate and House of Representatives approved a Republican-backed budget blueprint, with leaders eyeing $1.5 trillion is savings over 10 years. The blueprint does not specify what programs would be cut, but it calls for the House Energy and Commerce Committee, which oversees Medicaid, to find at least $880 billion in savings.

Now, members of Congress will get to work on crafting a bill detailing exactly how they will make that happen and disability advocates are bracing for a fight.

“We are deeply concerned that Medicaid will be targeted, putting critical services for individuals with autism and developmental disabilities at severe risk,” said Christopher Banks, president and CEO of the Autism Society of America. “Cuts of this magnitude could dismantle decades of progress in community-based care, leaving families without access to therapies, residential supports and essential health care.”

While President Donald Trump and other Republicans have said they won’t target Medicaid, it’s unclear how lawmakers could achieve the level of savings called for without cutting the program.

The nonpartisan Congressional Budget Office found that when Medicare is excluded, Medicaid accounts for 93% of mandatory spending under the House Energy and Commerce Committee’s purview. What’s more, the office concluded that the committee is expected to oversee only $581 billion in spending outside of Medicare and Medicaid meaning that there is no way to achieve $880 billion in cuts without touching either of the health programs.

The prospect of deep cuts to Medicaid has even some Republicans concerned.

“We cannot and will not support a final reconciliation bill that includes any reduction in Medicaid coverage for vulnerable populations,” a dozen House Republicans wrote in a recent letter to congressional leadership.

For people with disabilities, the stakes are especially high, advocates say. The Medicaid home and community-based services system serves as the backbone of supports for people with developmental disabilities in this country and it is already under tremendous strain.

Over 700,000 people are on waiting lists for Medicaid waivers, which provide home and community-based services, according to KFF, a nonprofit that conducts health policy research. And even those with waivers have struggled to get supports in recent years.

A national survey of nearly 500 community-based services providers released in December found that almost all had faced moderate or severe staffing shortages in the previous year. As a result, 69% had declined new clients and 39% closed programs or services, with over a third saying they were considering further cuts.

Home and community-based services are particularly vulnerable to any funding changes, advocates say, because they are considered optional Medicaid offerings under federal law.

“Cuts of this magnitude would force states to make harmful decisions, such as lowering provider payment rates, eliminating optional benefits, or restricting eligibility,” said Kim Musheno, senior director of Medicaid policy at The Arc of the United States. “Any reductions to this essential program risk undermining the ability of individuals with IDD to live with dignity in their communities. Services such as dental care, transportation, and respite are not luxuries; they are fundamental to quality of life. Cutting them would place unsustainable strain on families, direct support professionals, and state systems already stretched thin.”

Heather Sachs, co-director of policy and advocacy at the National Down Syndrome Congress, is warning that lawmakers are looking to act quickly.

“Congress is moving fast, and lives are on the line,” she said. “We’re in a fight for survival. The House Energy and Commerce Committee is set to begin markup on May 7, and these next few weeks are critical. We’re mobilizing across the country to make sure our voices are heard before it’s too late.”