WASHINGTON (AP) — Republicans are taking a big political risk on health care.

They're trying to scale back major benefit programs being used by millions of people. And they're trying to do it even though much of the public is leery of drastic changes, and there's no support outside the GOP.

It's not stopping them.

After seven years attacking former President Barack Obama's health care law, Republicans are finally in control of the entire government and say they have to deliver now. Yet they're not talking much about the trade-offs that come with sweeping changes, not to mention estimates that millions more people could be uninsured.

"I don't think anything of this consequence has ever been passed in the entitlement arena," said Jim Capretta, a health policy expert with American Enterprise Institute, a business-oriented think tank. "It's a piece of legislation that would be highly consequential."

Unprecedented "is a perfectly fair characterization," said Lanhee Chen, who was policy adviser to former GOP presidential nominee Mitt Romney. Like Capretta, Chen agrees with the general direction congressional Republicans are taking, if not all the specifics.

Senate Republicans are winnowing down policy options in search of 51 votes to advance House-passed legislation this summer.

Some of the central issues in the GOP's health care gamble:

HISTORIC SHIFT

Health care programs usually grow faster than other government services. Republicans want to break that decades-long trend, although they'd leave Medicare largely untouched for now.

The talk is all about repealing the 2010 Affordable Care Act. But the GOP's American Health Care Act would have lasting impact on Medicaid, the federal-state program covering about 70 million low-income and disabled people, including many elderly nursing home residents.

Republicans would phase out richer financing that the Obama-era law provides states that expand Medicaid to cover low-income adults. More significantly, the GOP would limit future federal spending for the broader program. Medicaid has been an open-ended entitlement, with the feds matching part of what every state spends, about 60 percent on average.

The House-passed GOP bill would cut $834 billion from projected federal Medicaid spending over a decade, leading to a reduction of about 17 percent in people covered by the program, according to the Congressional Budget Office.

"There is no capacity at the state level to pick up the slack if the federal government withdraws its commitment," Sen. Ben Cardin, D-Md., said at a recent budget hearing. Some Republican governors also question the plan.

Health and Human Services Secretary Tom Price said Medicaid can be more efficiently managed by the states, and that open-ended federal financing doesn't necessarily mean improved health for beneficiaries.

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GOALS AND OBJECTIVES

In addition to reducing federal health spending, Republicans want to lower premiums for those who buy their own health insurance, an estimated 20 million people. About half receive subsidies under the Obama law, but the rest pay full freight and many have seen steep premium increases stemming from changes under that law.

"Across America, premiums are skyrocketing, insurers are fleeing, and the American people are paying much more for much worse coverage," President Donald Trump said recently in Cincinnati.

Republicans would try to lower premiums by loosening some of the law's requirements, including standard benefits and a guarantee that those in poor health won't be charged more. People would be required to maintain "continuous coverage" to avoid penalties.

The CBO estimates that the GOP approach would lead to lower premiums than under current law, but the trade-offs could be significant.

Insurance, on average, would pay for a smaller share of health care costs, meaning that deductibles and copayments are likely to be higher. In some states, certain policies may not cover services such as substance abuse treatment. Over time, people with health problems might be priced out of the market.

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PROMISES, PROMISES

Trump's promise to repeal Obama's health overhaul was a fixture of his campaign. But he also said he was a different kind of Republican, who would not cut Social Security, Medicare, or Medicaid.

Later in the campaign, Trump announced support for a Medicaid block grant, a way of limiting federal spending on the program. But candidate Trump didn't elaborate on details, and repeatedly promised voters "great" health care.

The president again made that promise last week: "The Republicans are working very, very hard on getting a great health care plan," Trump said.

But health care policy is all about trade-offs, and Republicans have largely avoided talking about downsides. Democrats are ready to pounce.

"There are critical, life-changing decisions being made about Americans' health care right now in the United States Senate that should have people on high alert," Sen. Ron Wyden, D-Ore., said in this weekend's Democratic radio address. "This legislation is going to put the health of millions of Americans at risk."

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LONE RANGER RIDES AGAIN

Republicans never ceased complaining that Obama passed his law without a single GOP vote. Now, their bill has failed to garner any Democratic support. Not surprisingly, polls show that Democrats and independents disapprove of the legislation by wide margins.

"They're sending legislation through the Congress that is only supported by one party ... and somehow thinking it's going to have a different outcome," said economist Gail Wilensky, a Republican. "It's like, really, why would you think that?"