President Donald Trump's decision to end a provision of the Affordable Care Act that lowered out-of-pocket medical costs brought swift reaction Friday from the states, as health officials and consumers said they feared the action could chase millions of Americans away from coverage.

Attorneys general in nearly 20 states said they planned to sue the Trump administration to keep the money flowing, contending that the president is not following a legal requirement to pay the subsidies.

"This is a president who seems set on enacting reckless, unlawful campaign promises no matter the harm to families in America," Massachusetts Attorney General Maura Healey said during a conference call.

At issue is a federal subsidy for deductibles and co-pays that helps lower costs for consumers with modest incomes. The Trump administration and many Republicans say the government cannot legally continue to make the so-called cost-sharing payments.

State officials say ending the subsidies will make insurance premiums skyrocket, forcing some consumers to give up having coverage at all.

"Scared, anxious and worried," said Carmen Parra, a 64-year-old Miami nanny when asked for her reaction to Trump's decision.

The federal cost-sharing payments cover nearly 95 percent of her deductible and co-pay costs. For example, she pays just $2 each for blood pressure and asthma medications, and an urgent care visit for one asthma attack costs just $15.

Without the subsidies, Parra said she could be forced to go without insurance. Her state has led the country in insurance enrollment under the Affordable Care Act, nearly 1.7 million consumers signing up for coverage. About three-fourths of them receive federal subsidies of some kind.

"Please consider the people who need this assistance so they can live. Our lives depend on it," Parra said in Spanish through a translator.

Trump's announcement Thursday came weeks after the failure of the latest Republican attempt to repeal former President Barack Obama's Affordable Care Act. It's less than three weeks before the start of open enrollment, when many Americans who do not have health insurance through their employers can start picking their plans.

The payments to insurance companies are a major piece of Obama's overhaul, which extended coverage to low- and moderate-income people in multiple ways. More than 6 million people benefit from the cost-sharing subsidies, which cost the federal government about $7 billion a year. That cost is expected to more than double within a decade.

Cost-sharing is aimed specifically at people who buy coverage on government run exchanges and make between 100 and 250 percent of the federal poverty level — between about $12,000 and $30,000 for single people.

The program is distinct from two other major subsidies provided under the Affordable Care Act that were not affected by Trump's order. One has the federal government picking up most of the cost to expand Medicaid to a larger group of low-income people in states that chose to participate. The other gives tax credits to most people who buy individual coverage on the government-run insurance exchanges to help lower their monthly premium costs.

Trump's decision to end the funding immediately may have been a surprise, but he's been considering cutting the payments for months. A group of Democratic state attorneys general — already fighting Trump policies on many other fronts — had earlier this year entered the legal battle to try to preserve the cost-sharing measures. But insurers in several states set their rates for offerings on the exchange for 2018 assuming the subsidies would vanish by then.

In Wisconsin, officials said Thursday — just before Trump's announcement — that the expected cuts were a major reason the premiums for plans on the exchange were jumping by an average of 36 percent. Sen. Tammy Baldwin, a Democrat, called it "sabotage of the health care market" by the president.

Gov. Scott Walker, a Republican, placed the blame on the system that Trump is deconstructing.

"Obamacare has failed to deliver on its promise of affordable health care year after year," said his spokesman, Tom Evenson.

A study from the Kaiser Family Foundation earlier this year found that premiums for "silver" plans on the healthcare exchanges would go up by an average of 19 percent to offset the loss of the deductible and co-pay subsidy. In states where rates have been announced, there's been a wide variation, even among insurers expecting the cuts. In Arizona, for instance, average premiums on the exchange are rising by less than 2 percent for one company and will go down by 1 percent for another.

Even as they sue, many officials are still advising consumers to buy coverage under the exchanges after enrollment opens Nov. 1.

The timing of Trump's announcement just before that period concerns those who advocate for continuing the cost-sharing subsidies.

"His effort to gut these subsidies with no warning, or even a plan to contain the fall-out, is breathtakingly reckless," New York Attorney General Eric Schneiderman said Friday.

New York and California are among the states filing the lawsuit in federal court in California. Others joining the action are: Connecticut, Delaware, Iowa, Illinois, Kentucky, Maryland, Massachusetts, Minnesota, New Mexico, North Carolina, Oregon, Pennsylvania, Rhode Island, Vermont, Virginia, Washington and the District of Columbia.

The subsidies are essential for many health care consumers.

Dawn Erin, a 46-year-old massage therapist in Austin, Texas, is among them. After going nearly two decades without insurance, she now has coverage through the federal marketplace. That's what covers her $70,000 annual bill for drugs to treat hepatitis C, as well as appointments with specialists.

"I'm disgusted but not surprised," Erin said Friday about Trump's decision to end the payments. She said the president "wants to scribble his name on anything that will take apart anything with Obama's name on it."

She now fears she might have to return to having no insurance and rely instead on sporadic charity care.

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Kennedy reported from Fort Lauderdale, Florida.

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Also contributing were Associated Press writers Jim Anderson in Denver, Scott Bauer in Madison, Wisconsin, and Colleen Long in New York City.