WASHINGTON—House and Senate leaders announced late Friday night that they had finally hammered out a deal on landmark legislation designed to speed federal approval of new drugs and devices and boost funding of medical research.

But what Republican lawmakers call the “final” version of the 21st Century Cures Act is actually still in negotiation with Senate Democrats, a senior Democratic aide told STAT on Sunday.

Despite the potential for challenges in the Senate, the House will push ahead and vote Wednesday on the $6.3 billion legislation. It would give states $1 billion to fight the opioid crisis, in addition to providing $4.8 billion for continuing three signature Obama administration research programs over the next 10 years: Vice President Joe Biden’s cancer moonshot, the BRAIN Initiative, and the Precision Medicine Initiative.

The Cures Act also includes a $500 million increase for the Food and Drug Administration and a number of programs to improve mental health care, including suicide prevention on college campuses and screening pregnant women for depression.

In a joint statement Friday, Tennessee Republican Senator Lamar Alexander, chairman of the Committee on Health, Education, Labor and Pensions, and Michigan Representative Fred Upton, chairman of the Energy and Commerce Committee, said they expect the landmark legislation to be approved by the end of the year.

“America’s patients are waiting on us and we will deliver,” they declared.

The Cures Act, which passed the House by a landslide in July 2015, has been the focus of dozens of congressional hearings and endless debate among Republicans and Democrats over the past three years.

During this time, more than 1,300 lobbyists have roamed the halls of Congress, pressing for passage on behalf of pharmaceutical companies, medical device firms, and patient advocacy groups.

They were joined in their effort by a parade of celebrities, from legendary rock ’n’ roll star Roger Daltrey to former junk-bond-king-turned-medical-philanthropist Michael Milken—a major force in getting congressional leaders fired up about the issue.

Leaders from both parties have called passage of the Cures bill the most important thing Congress could do this year. Both Alexander and Upton consider it their legacies. Although Alexander will remain chairman of his committee next year, Upton will have to step down.

But there has been a major sticking point: While the House version of the bill included funding for medical research, which the Democrats required for their support, Senate Republicans on the HELP committee would not approve funding without an agreement over where the money would come from.

The lack of financing caused a stalemate until the unexpected happened: The Affordable Care Act was mortally wounded by the election of Donald Trump. With huge chunks of Obamacare now likely to be repealed, Democrats have agreed to underwrite the Cures Act with some money from the ACA, and some to be generated by sales of part of the Strategic Petroleum Reserve.

“What we have in the 21st Century Cures Act is an innovation game changer, a transformational bill to bring our health infrastructure light years ahead,” said Upton and Alexander.

The Democrats have been silent on the so-called final version of the Cures Act. They have long been worried about provisions to speed the Food and Drug Administration’s approval process—concerns that have increased with the election of Trump, who has said he plans to reduce government regulation.

Some consumer groups contacted Sunday said they still oppose the legislation. They fear the medical research money is buying the Democrats’ acquiescence on important FDA safety matters.

“While there are positive aspects of this legislation, many provisions would severely weaken the FDA’s drug and medical device approval standards and seriously harm rather than help patients,” said Jack Mitchell, director of government relations for the National Center for Health Research, which advocates for patient safety. “Congress shouldn’t sacrifice the safety and effectiveness of medical products in order to increase research monies.”

Final or not, many of the bill’s provisions are aimed at the FDA. It establishes an expedited review for breakthrough medical devices, increases patient participation in the drug approval process, and calls for streamlined review for drug-device combinations.

The Cures Act would require the FDA to evaluate the use of so-called “real-world” evidence to help support new uses for previously approved drugs, and to help support or satisfy post-approval requirements to confirm the safety and effectiveness of treatments. Many public health advocates see this as a weaker alternative to the current gold standard of randomized clinical trials.

More controversially, it would allow the FDA to accelerate approval of regenerative advanced therapies, or stem cell therapies, a measure pushed by Senate Majority Leader Mitch McConnell of Kentucky. The provision draws on the REGROW legislation originally sponsored by Illinois Republican Senator Mark Kirk, who had suffered a debilitating stroke.

The REGROW provisions in the Cures Act call for devices used with a stem cell product to be considered moderate risk, unless the secretary of Health and Human Services determines that the device or use requires a higher risk classification.

Opponents believe applications of regenerative medicine, which seek to restore or establish normal function in damaged human cells, tissues and organs, should be closely regulated and subject to clinical trials.

Republished with permission from STAT. This article originally appeared on November 27, 2016