Vulnerable and moderate House Republicans are warning House GOP leaders that they will not support the “one big, beautiful bill” encompassing President Trump’s legislative agenda if it includes cuts to Medicaid benefits.

Twelve House Republicans in competitive districts more than enough in the House GOP’s razor-thin majority to keep the bill from passing sent a letter to Speaker Mike Johnson (R-La.), House Majority Leader Steve Scalise (R-La.), House Majority Whip Tom Emmer (R-Minn.), and Energy and Commerce Committee Chair Brett Guthrie (R-Ky.) on Monday articulating that red line.

“We cannot and will not support a final reconciliation bill that includes any reduction in Medicaid coverage for vulnerable populations,” the members said in the letter led by Rep. David Valadao (R-Calif.) and Rep. Don Bacon (R-Neb.), which was first reported by Punchbowl News and obtained by The Hill.

The warning comes as Republicans in Congress are starting to craft details of the reconciliation bill set to include key parts of Trump’s agenda, including extension of tax cuts and border funding. The House last week cleared a budget resolution framework for the measure, despite steep demands from fiscal hawks for spending reductions to offset the cost of other priorities cuts many moderates worry could threaten Medicaid coverage their constituents rely on.

“Balancing the federal budget must not come at the expense of those who depend on these benefits for their health and economic security,” the members said.

The budget blueprint approved last week directs the House Energy and Commerce Committee, which has jurisdiction over Medicaid, to locate $880 billion in spending cuts over the next decade a figure that analysts say is mathematically impossible without making changes to Medicaid, which provides health coverage to low-income individuals.

Republican leaders say they only want to root out waste, fraud, and abuse in Medicaid, and to implement work requirements for nondisabled adults. Those who signed the letter noted their agreement for some reforms.

“We acknowledge that we must reform Medicaid so that it is a strong and long-lasting program for years to come. Efficiency and transparency must be prioritized for program beneficiaries, hospitals, and states. We support targeted reforms to improve program integrity, reduce improper payments, and modernize delivery systems to fix flaws in the program that divert resources away from children, seniors, individuals with disabilities, and pregnant women – those who the program was intended to help,” the members said in the letter.

Later in the letter, the members said they are willing to “identify responsible savings” in Medicaid “through deregulation, streamlining federal programs, and cutting administrative red tape.”

But Democrats are digging in hard on plans by Republicans to cut Medicaid and those in competitive districts are clearly feeling the pressure.

Along with Valadao and Bacon, the Republicans who signed the letter are largely moderate members from the more competitive districts in the country: Reps. Jeff Van Drew (N.J.), Rob Bresnahan (Pa.), Juan Ciscomani (Ariz.), Jen Kiggans (Va.), Young Kim (Calif.), Rob Wittman (Va.), Nicole Malliotakis (N.Y.), Nick LaLota (N.Y.), Andrew Garbarino (N.Y.) and Jeff Hurd (Colo.).

“Cuts to Medicaid also threaten the viability of hospitals, nursing homes, and safety-net providers nationwide. Many hospitals—particularly in rural and underserved areas—rely heavily on Medicaid funding, with some receiving over half their revenue from the program alone. Providers in these areas are especially at risk of closure, with many unable to recover. When hospitals close, it affects all constituents, regardless of healthcare coverage,” the members said.

“To strengthen Medicaid, we urge you to prioritize care for our nation’s most vulnerable populations. Our constituents are asking for changes to the healthcare system that will strengthen the healthcare workforce, offer low-income, working-class families expanded opportunities to save for medical expenses, support rural and underserved communities, and help new mothers,” they added.