Gov. John Hickenlooper on Wednesday urged U.S. House Majority Leader Kevin McCarthy to resist repealing the Affordable Care Act until an adequate replacement is identified.

Hickenlooper joins a chorus of Democrats who fear that the GOP-controlled Congress, with help from Republican Donald Trump, will prematurely dismantle the federal health care law.

“Because of the progress Colorado has made, repealing the Affordable Care Act without an immediate replacement may be disastrous,” Hickenlooper wrote in a letter to McCarthy.

Colorado Commissioner of Insurance Marguerite Salazar joins Hickenlooper in signing the letter.

McCarthy and other Republican leaders sent a letter to state governors and insurance commissioners in early December requesting ideas for how to reform the nation’s health care system.

“As Obamacare continues to saddle patients with less choice, higher costs and mountains of mandates, it is clear that major health care reforms must be made to strengthen and improve health care for all Americans,” McCarthy’s letter read.

Hickenlooper said repeal of the ACA could lead to the collapse of Colorado’s individual health insurance marketplace, which the state developed in 2011 in an effort to carve its own path forward implementing federal health reform.

“We urge you to protect health care coverage for the over 600,000 Coloradans that have gained coverage under the Affordable Care Act,” Hickenlooper wrote. “We simply cannot support efforts to repeal current law without a plan to immediately protect Coloradans.”

Colorado Republicans, however, do not appear worried about a lapse in coverage, suggesting that there are free market solutions to fill the void.

“We solve it with less government,” said Colorado House Republican Leader Patrick Neville of Castle Rock. “We need to have more competition, maybe look at out-of-state plans… more options instead of having a one-size-fits-all plan for everyone.”

But Hickenlooper says Medicaid expansion has led to historic coverage levels, and that the Affordable Care Act reduced growth in health care costs.

He has support from a new coalition of more than 100 groups across the state – the Colorado Health Policy Coalition – which also recently urged Congress not to repeal the ACA without a comprehensive replacement plan. The diverse coalition includes health care and business organizations with representation from both political parties.

“Our first, most urgent message has to be that repeal of our existing framework, without a clear picture of what will replace it, is a recipe for disaster,” said Adela Flores-Brennan, executive director of the Colorado Consumer Health Initiative.

“The business community is acutely aware of the important decisions that will happen soon and we’re anxious to make sure Congress hears our voice on these issues,” added Kelly Brough, president and chief executive of the Denver Metro Chamber. “It is critical that we maintain functional health insurance marketplaces that provide affordable coverage for Coloradans and ensure our entire state is a great place to live, work and practice medicine.”

Hickenlooper added that he is open to giving states more flexibility to improve health care and innovate, but that “greater flexibility cannot make up for a lack of funding.” There are fears that Republicans will reduce funding for Medicaid, which would force the state to “make impossible choices,” according to Hickenlooper.

“Should the federal government pull back its financial commitments, we simply cannot afford to make up the difference…” the governor stated. “We should not be forced to choose between providing hardworking older Coloradans with blood pressure medication or children with their insulin.”