Hempstead was referring to two main pillars of the Affordable Care Act.
The first was the creation of government-run insurance marketplaces to sell individual health plans. Tax credits, or subsidies, are available to low and middle-income customers of those plans, which can often significantly reduce the actual premiums they pay personally.
The second components was expanding joint federal-state Medicaid programs to expand eligibility of those programs to include nearly all poor adults, most of whom will pay no or little out-of-pocket costs for their coverage. Almost 30 states have adopted Medicaid expansion so far.
Both Medicaid expansion and the Obamacare exchanges have been credited with significantly reducing the rate of Americans without health insurance in 2014.
The Kaiser Family Foundation report released Thursday found that while those features had led to 11 million adults getting insurance in 2014 after lacking it, other factors were keeping the remaining 30 million or so adults from obtaining insurance.
Kaiser's report said that "48 percent of the roughly 30 million adults remaining uninsured at the end of 2014 were eligible for assistance under the law."
That included "30 percent who were eligible for marketplace tax credits, and 18 percent who were eligible for Medicaid," the report said. "And yet they did not get coverage."
The study found several key reasons for that.
A total of 53 percent of the uninsured eligible for help cited the perceived cost of health insurance generally as the primary reason they didn't have coverage.
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And while some of those people who were eligible had in fact sought coverage, 37 percent of that group "say they were told they ineligible," the report found.
"While it is possible that they were ineligible at the time they applied, it is likely that these people received incorrect information or misinterpreted information they were given," according to Kaiser.
Rachel Garfield, a senior researcher at Kaiser, said, "The findings show how important it is to come up with more effective strategies, in person, online and elsewhere, for educating people about the eligibility for coverage and financial assistance under the law."
Kaiser noted nearly 4 million of the remaining uninsured are in a so-called "coverage gap." That means they live in non-Medicaid expanding states and earn too much to be on the Medicaid programs there, but also earn less than the income threshold for qualifying for Obamacare subsidies to buy coverage on government exchanges. Other uninsured people are undocumented immigrants, who are not eligible for Obamacare.
"No matter how well the ACA works, there are still substantial numbers of uninsured people with no affordable option for health coverage," said Kaiser Executive Vice President Diane Rowland.