As the U.S. Senate opened a hearing Monday on a health care bill aimed at dismantling the Affordable Care Act, Gov. Mark Dayton blasted the proposal as a “sham” that would force states like Minnesota to cut health coverage for large numbers of residents.

Backed by Minnesotans who depend on the federal Medicaid program to cover their health care costs or those of their children, the DFL governor said the Graham-Cassidy bill takes direct aim at a program that provides health care for the elderly, people with disabilities, low-income residents and one-third of Minnesota children. The bill would cut the Medicaid expansion that Dayton signed into law on his second day in office, which now covers about 200,000 people in the state, and eliminate federal support for MinnesotaCare, the state’s basic health plan for the working poor.

“It’s a terrible, terrible undertaking of the Trump administration and the Republican majorities in the U.S. House and Senate,” Dayton said, “to devastate health care for millions of Minnesotans and Americans.”

An analysis released Monday by the state Department of Human Services estimates the proposal would cut federal funding for programs that cover health care for about 366,000 Minnesotans, and lump that group together with another 900,000 Minnesota residents who receive Medicaid support. That entire group would share in a single federal block grant that officials say would amount to less money than the state currently receives.

Dayton said that system, which would go into effect in 2020, would force state leaders to make “terrible” cuts.

Sen. Michelle Benson, R-Ham Lake, chairwoman of the state Senate’s Health and Human Services Finance and Policy Committee, said she agreed with Dayton that “the people truly in need, need a sustainable system.”

She said federal reforms should be focused on ensuring people who need care most are prioritized, rather than “competing for limited resources with people who can make their own way.”

Sen. Jim Abeler, R-Anoka, a member of Benson’s committee, said he likes the idea of Minnesota having more control over how it doles out health care dollars — as long as the state’s grant is of a “reasonable size.”

“I am a fan of block grants,” he said. “Minnesota should have control of how it spends its money. Federal involvement has only harmed Minnesota’s health care system.”

But some of the people who spoke alongside the governor on Monday aren’t so confident.

Marc Gorelick, the president and chief operating officer of the Children’s Minnesota health system, said about half the young patients at Children’s hospitals and clinics receive coverage through Medicaid. He said he’s concerned the Graham-Cassidy bill would include significant cuts for coverage for prenatal care and for babies born with serious medical conditions.

“In my 30 years in pediatrics, I don’t think I’ve seen a threat to children’s health care quite like this one,” he said.

Kate Swenson, a Cottage Grove mother of a 6-year-old boy with severe autism, said the debate over Medicaid cuts is causing her family considerable stress. Swenson has private health coverage through her employer, but it doesn’t cover the autism-specific program that her son needs, so he receives Medicaid coverage.

“It is keeping me up at night, and I’m surprised I don’t have an ulcer,” Swenson said.