A bill to improve the country’s mental health care system could be undermined by more widespread changes to health coverage that will likely occur next year, supporters of the effort fear.

The Senate is expected this week to clear the “21st Century Cures” package, a medical innovation bill that also includes provisions designed to make it easier for patients to access mental health treatment.

Some of the bill’s supporters lament that the provisions wouldn’t increase federal funding for inpatient treatment, but there is widespread support for other items that would integrate mental health into primary care services, train new behavioral health providers and train law enforcement and the legal system to better deal with crime related to mental health problems.

All of that would be less meaningful if Republicans roll back President Barack Obama’s health care law and people lose coverage, said Rep. Frank Pallone Jr. of New Jersey who, as ranking Democrat on the Energy and Commerce Committee, played a major role reaching a compromise on the mental health legislation.

“This is a great bill, and we worked on it a lot, but it’s not going to be worth much if we repeal the Affordable Care Act,” Pallone said at a House Rules Committee hearing last week.

The biggest fears surround potential changes to Medicaid, which some states were able to expand with federal support provided by the 2010 health care overhaul. President-elect Donald Trump has called for providing federal funding to state Medicaid programs through block grants, which are viewed by many as a way to keep funding flat.

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Medicaid pays for around 60 percent of the nation’s mental health services. While one in five Medicaid beneficiaries have behavioral health diagnoses, they often have multiple chronic conditions and account for about half of overall Medicaid spending.

“Anything that rolls back the Medicaid expansion will have a devastating impact for people with mental illness and substance use disorders getting the care that they need,” said Chuck Ingoglia, senior vice president for public policy at the National Council for Behavioral Health.

In a call with reporters on Thursday, one of the senators who helped get the mental health bill to the finish line expressed similar concerns.

“I’m personally worried about the block granting of Medicaid and what that will mean to the amount of money that Connecticut has to run a mental health system,” said Democratic Sen. Christopher S. Murphy of Connecticut, who also feared that future Medicaid cuts could also result in less coordination between the physical and behavioral health systems.

Louisiana GOP Sen. Bill Cassidy, who partnered with Murphy on the mental health bill, has offered a health care law replacement of his own that he hopes would help prevent states from rolling back coverage. It would place a per-capita spending limit on Medicaid funding, but would allow for extra payments for people with particularly high medical costs.

“If you’ve got a recession and a lot more people are joining Medicaid rolls, then your per-beneficiary block grant increases, and you should risk-adjust that,” Cassidy said.

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Rep. Tim Murphy, the Pennsylvania Republican behind the mental health effort in the House, acknowledged that GOP lawmakers will have to be careful as they work to repeal and replace the health care law. But he thinks next year’s health overhaul will be a chance to build on the mental health bill and continue to move toward payment models that reimburse based on quality of care instead of fees for services rendered, and better integrate behavioral health into primary health care.

Murphy said some of the changes Republicans are considering, such as emphasizing the use of health savings accounts won’t work for people with serious mental illness who can’t manage their own affairs. Mental health advocates don’t want to see a repeal of the current health system, but some agree with Murphy that some fundamental changes are necessary.

“Until you build a system that actually rewards people for staying healthy and moves people who get sick as quickly to recovery as you possibly can, you’re not going to do anything more than tinker with the payment system and fix them around the edges,” said Paul Gionfriddo, president of Mental Health America, a nonprofit focused on community care.

Some advocates are concerned that protections under the health care law will be lost. They worry that people will lose coverage for depression or substance abuse screenings. If insurance could be sold across state lines, something that Trump supports, some worry that plans will be based out of states where regulatory protections are weakest, harming the enforcement of parity laws meant to ensure that mental health care is covered to the same extent as physical health services.

“That would have the potential for the greatest amount of damage, particularly in those states that have had the best access to care,” Gionfriddo said.