SANTA FE, N.M. (AP) — New Mexico stands to lose critical funding for substance abuse treatment that has helped combat a local opioid epidemic, under a Republican campaign on Capitol Hill to roll back President Barack Obama‘s health care law.

A House-approved health care bill would phase out expanded Medicaid that allows states to provide federally backed insurance to low-income adults. Federal Medicaid expansion dollars have allowed key states to boost their response to the opioid crisis, paying for medication, counseling, therapy and other services.

In New Mexico, the expansion accounted for 21 percent of Medicaid spending on behavioral health — a category that includes mental health and substance abuse — in the year ending in June 2016. The state Human Services Department says that translates into $101 million out of $477 million in behavioral health spending. Numbers specific to addiction treatment were not available.

State officials estimate that behavioral health services have been extended to reach 75 percent more people since Medicaid was expanded at the start of 2014.

In 2014, New Mexico had the second-highest overdose death rate behind West Virginia, according to the federal Centers for Disease Control and Prevention. In 2015, seven other states had higher overdose rates.

Wayne Lindstrom, director of the New Mexico Behavioral Health Services Division at the state agency overseeing Medicaid programs, predicted a major setback for substance abuse treatment and other behavioral health programs if Republicans do away with the federal Medicaid expansion funding.

“It concerns me with all of the discussion going on in Washington, potentially block granting Medicaid, potentially doing away with Medicaid expansion, because this would be devastating for the behavior health field,” he told a panel of state lawmakers this month. “If Medicaid is significantly dismantled and there are significant cutbacks, it’s going to have huge ramifications for us.”

New Mexico’s annual state budget includes an escape clause allowing the state to rescind Medicaid eligibility for adults if federal support for the expansion is rolled back.

New Mexico state Sen. Gerald Ortiz y Pino, D-Albuquerque, said he fears treatment for substance abuse would be among the first services to be eliminated by the state if federal aid is rolled back.

“A lot of those services are not mandatory. We don’t have them in state law or federal law,” he said Tuesday. “Those tend to get short shrift if we have to cut back. I think they might be the first things to go.”

New Mexico’s delegation to Washington is divided along partisan lines over the GOP health care overhaul, with Democratic Sens. Tom Udall and Martin Heinrich on Tuesday describing potentially devastating consequences.

Republican U.S. Rep. Steve Pearce, who voted for the House bill, said expansion funding would decrease only for people who drop Medicaid coverage and then return. “Individuals impacted by opioid addiction, and everyone else who gained coverage under Medicaid expansion, will continue to receive care as long as they stay on the program,” he said in an email.

Jonathan Willoughby, a staff therapist at a for-profit, Medicaid-supported center in Albuquerque that treats court-ordered patients for substance abuse problems, said staff and patients confront an uncertain future. “Most if not all our clients would end up incarcerated again” if the program were defunded, he said.