The bill would also, for the first time ever, apply a per-person limit on how much the federal government spends on Medicaid. This change could shift about $370 billion in health care costs over 10 years to state governments, according to the Center on Budget and Policy Priorities. Many state governments, faced with limited budgets, would be forced to cut benefits or cover fewer people.

For people who buy insurance on federal or state-run health exchanges, the G.O.P. plan would greatly reduce the A.C.A.’s subsidies, which come in the form of tax credits. For example, a 40-year-old living in Raleigh, N.C., who earns $30,000 a year would receive $3,000 from the government to buy insurance, 32 percent less than under current law, according to the Kaiser Family Foundation. The bill would provide older people more generous subsidies — those over 60 get a subsidy of $4,000, or twice as much as 20-somethings — but insurers would be allowed to charge older people five times as much as younger people.

The plan would do away with the current mandate that requires nearly everybody to obtain insurance or pay a penalty. (Instead, insurers would be allowed to charge people who don’t maintain their insurance continuously 30 percent more for coverage.) But because the legislation would still require insurers to cover pre-existing conditions, people would have a strong financial incentive to buy insurance only when they got sick — a sure way to destroy the insurance market.

House Speaker Paul Ryan and Tom Price, the secretary of health and human services, have railed against high premiums and deductibles for plans sold on the health exchanges, but that problem would only worsen under their proposal because insurers would almost certainly raise their prices as the pool of the insured shrank. Republican lawmakers seem to think that people who can’t afford insurance are simply irresponsible. Representative Jason Chaffetz of Utah, for instance, told CNN that people should invest in their health care, “rather than getting that new iPhone.” Word to Mr. Chaffetz: Health insurance costs more than $18,000 a year for an average family; an iPhone costs a few hundred dollars.