WASHINGTON — Republicans trying to dismantle former President Barack Obama’s health care law have run into the same problem that bedeviled him: Quality health insurance doesn’t come cheap, especially if it protects people in poor health, older adults not yet eligible for Medicare, and the poor.

Something has to give.

Now, the GOP’s laser focus on lowering premiums could undermine comprehensive coverage that consumers also value, such as the current guarantees that people with medical problems can get health insurance, or that plans will cover costly conditions such as substance abuse.

“Premiums do not tell the whole story,” said Trish Riley, executive director of the National Academy for State Health Policy, a nonpartisan organization that advises states.

“The questions that need to be addressed are what do those premiums buy, and what other costs besides premiums do consumers pay?” said Riley. “If you buy a bike it will cost you less than a car.”

With “ObamaCare,” Democrats set out to get more people insured, but they also wanted to bolster the underlying coverage by making it illegal for insurers to turn away those with medical problems, requiring a broad range of standard benefits, and establishing a baseline of financial protection. Previously, for example, people with a history of cancer could be charged a higher premium, or be turned down altogether.

That led to 20 million more insured, but also higher premiums for people buying their own policies, along with tax increases and considerable federal regulation.

Republicans trying to roll back the 2010 health care law are making their case all about premiums, trying to find ways to give states and insurers flexibility to design plans that cost less. About half the people who buy individual health insurance policies are subsidized under Obama’s health law, but the rest are not, and many have faced stiff premium increases.

The old saying about getting what you pay for still applies.

Although many healthy customers would welcome plans with lower monthly premiums, the high cost of medical care isn’t going down. The risk is that the GOP’s premiums-focused approach will undermine comprehensive coverage that consumers also want, since no one is beyond the reach of sickness, or immune from the consequences of age.

A nonpartisan analysis of the House-passed Republican bill put the stakes in sobering terms. The Congressional Budget Office said that in states that take full advantage of the House plan’s waivers to insurance requirements, healthy people might flock to skinnier, lower-premium plans.

Those in poor health left in comprehensive plans could face premiums that keep rising until they become unaffordable, because there would be fewer healthy people in those plans to share the cost.

“People who are less healthy (including those with pre-existing or newly acquired medical conditions) would ultimately be unable to purchase comprehensive ... health insurance at premiums comparable to those under current law, if they could purchase it at all,” said the CBO report.

With polls showing that only about 1 in 5 five Americans support the House bill, Republicans still have many issues to resolve.

Even Ryan, one of the bill’s biggest cheerleaders, acknowledges that. “We got two problems we got to solve here,” he said later in his news conference. “We got to get premiums down and we got to make sure that people with pre-existing conditions can get affordable coverage.”