Even as turmoil in insurance markets nationwide fuels renewed election-year attacks on the Affordable Care Act, California is emerging as a clear illustration of what the law can achieve.
The state has recorded some of the nation's most dramatic gains in health coverage since 2013 while building a competitive insurance marketplace that offers consumers enhanced protections from high medical bills.
Californians, unlike people in many states, have many insurance choices. That means that even with rising premiums, the vast majority of consumers should be able to find a plan that costs them, at most, 5% more than they are paying this year.
And all health plans being sold in the state will cap how much patients must pay for prescriptions every month and for many doctor visits.
That reflects deliberate choices by California state officials who, unlike many states, used the health law to expand the Medicaid safety net and build a marketplace that put stringent requirements on insurance companies.
"California followed the blueprint. They did it right," said Dr. J. Mario Molina, chief executive of Long Beach-based Molina Healthcare Inc., a leading national insurer that is selling marketplace plans in nine states in 2017.
"What has been lost in all the rhetoric and the politics is that the system can work," Molina said. Open enrollment begins next month.
California and its Obamacare marketplace, Covered California, still face challenges, including rising costs. Like consumers elsewhere, some Californians, particularly those who make too much money to qualify for government subsidies, are seeing substantial premium increases and narrowing networks.
But while health coverage has faltered in other states where politicians worked to undermine the law, California highlights what can be accomplished if government officials and industry leaders work together to expand insurance, control costs and protect consumers.
Many of the advances being pioneered in California have been incorporated into Democrat Hillary Clinton's program to improve on the Affordable Care Act if she is elected president.
"We're not just the biggest state and one of the states that's most aggressively taken advantage of tools in the Affordable Care Act," said Health Access California Executive Director Anthony Wright, a leading consumer advocate. "We are also one of the states that had the biggest problems to start with.
"Now we're showing that you can use the law as a platform to benefit patients."
Between 2013 and 2015, the share of working-age adults in California without coverage plummeted from 23.7% to 11.1%, according to federal data. Only three states saw larger declines over the same period.
The new coverage has dramatically improved patients' access to medical care and reduced financial strains, other research indicates.
More than three-quarters of newly insured Californians said their health needs are now being met, a recent survey by the nonprofit Kaiser Family Foundation found.
By contrast, less than half said they were getting needed care before they got coverage through the health law.
At the same time, Californians who gained coverage reported fewer worries about paying for not just healthcare, but also housing, transportation, even food.
For Del Hunter-White, a Los Angeles actress who lost her insurance through the Screen Actors Guild when she didn't work enough to qualify for the union plan, Covered California opened just in time.
"It was a lifesaver," she said, noting she probably wouldn't have been able to get coverage. "At my age, you don't want to go without insurance."
Hunter-White, who is 60, found a health plan that costs her $195.87 a month and allows her to see the doctors she wants. "It's been great," she said.
Overall, nearly 8 in 10 newly insured Californians feel positively about their coverage, Kaiser found.
Much of the insurance expansion in California has been fueled by the state's decision to take advantage of federal funding in the health law to expand Medicaid eligibility to poor, childless adults, a population traditionally excluded from most states' safety nets.
But Covered California has also played a critical role, with about 1.3 million direct customers and nearly 1 million more who get health plans that must meet Covered California standards even though consumers don't use the marketplace to purchase them.
The large enrollment isn't an accident.
Many states now facing the biggest problems with their insurance markets actively resisted the health law, refusing to expand Medicaid or to help build a new marketplace where consumers could shop for health plans.
By contrast, state leaders in California, including former Republican Gov. Arnold Schwarzenegger, decided early that California's insurance marketplace would set high standards for health plans and actively negotiate to control prices.
In the first two years of the marketplace, premiums increased an average of just 4%.
The state made a difficult decision to terminate old plans that didn't meet the health law's higher standards, a crucial move that helped stabilize the market by bringing the healthier consumers who had these plans into the larger risk pool.
The state also worked closely with foundations, consumer advocates, hospitals and insurers to enroll customers, particularly younger, healthier people who are also critical to maintaining a good risk pool and keeping premiums in check.
"We all worked together to make sure the marketplace worked," said Jay Gellert, former chief executive of Los Angeles-based insurer Health Net Inc., which merged this year with Centene Corp.
Now, Covered California is implementing consumer protections that exempt many routine office visits from deductibles.
That means that someone who has a health plan with a $2,500 deductible can still see a primary care doctor for just a $35 copay and see a specialist for just $70.
Covered California Executive Director Peter Lee said these new protections should make the health plans more appealing to customers who might have been resistant to buy a plan that required them to pay thousands of dollars out of their own pockets before they got any protection.
"No patient I know wants to pay $2,500 to see the doctor," Lee said.
Lee and others acknowledge that even the new protections won't alleviate all cost pressures on health plans and consumers.
In 2017, Covered California rates are increasing an average of 13.2%, driven in part by rising medical costs and the end of a federal program that helped hold down rates.
Premiums for several insurers, including Blue Shield of California and Anthem Inc., are increasing even more dramatically.
Preventing large rate hikes in the future will require adjustments to the marketplaces in California and elsewhere, many experts say.
But many states could start by taking steps California already has to make their markets work, said Molina, the health plan executive.
"Had states like Texas and Florida followed California's lead, they might have seen more gains like California's," he said.