Leading hospital groups teamed up to warn President-elect Trump this week that repealing the Affordable Care Act could spark an “unprecedented public health crisis,” and cost the hospital industry billions of dollars.

The two hospital trade groups—the American Hospital Association (AHA) and the Federation of American Hospitals (FAH)—even commissioned a study by an outside economics consulting firm to put real numbers to the losses. Their study, conducted by the Dobson | DaVanzo firm, modeled what would happen if the government enacted the ACA-demolishing legislation introduced by Trump’s nominee for Secretary of Health and Human Services, Tom Price (R-Ga.); the legislation was vetoed by President Obama in January.

The study’s verdict: 22 million people would lose insurance by 2026, which would cost hospitals $165.8 billion. And, because the legislation wouldn’t undo certain payment cuts created by the ACA, hospitals would lose an additional $102.9 billion.

In a letter sent this week to Trump, AHA President and CEO, Rick Pollack, and FAH President and CEO, Chip Kahn, wrote:

“Losses of this magnitude cannot be sustained and will adversely impact patients’ access to care, decimate hospitals’ and health systems’ ability to provide services, weaken local economies that hospitals help sustain and grow, and result in massive job losses.”

To avoid this dire scenario, Pollack and Kahn implored the President-elect to only repeal the ACA if there’s a ready replacement that will guarantee coverage to the millions who gained it.

Trump said during his campaign that he intended to swiftly repeal and replace the massive law once he took office. However, he has not provided a plan for how to do that or released any draft legislation for a possible replacement. And Republicans are themselves torn on what a replacement should look like.

Right now, the GOP has reportedly embraced a strategy to quickly repeal the ACA once Trump takes office in January, but then delay the need for a replacement by initiating an ACA-phase out over several years.

Experts warn such a plan could cause massive anxiety in the industry and destabilize the market.

In a recent healthcare poll conducted by the Kaiser Family Foundation, only 26 percent of respondents supported a complete repeal of the ACA. Seventeen percent wanted a scale-back, while 19 percent said politicians should leave it alone, and 30 percent said they wanted the ACA to be expanded.