In this Aug. 13, 2019, file photo a worker gets ready to pass out instructions in how fill out the 2020 census during a town hall meeting in Lithonia, Ga. Credit: John Amis | AP

The proportion of Americans without health insurance grew significantly last year for the first time this decade, according to new federal figures that show the number of people lacking coverage rose to 27.5 million.

The findings released Tuesday, based on a large U.S. Census Bureau survey measuring Americans’ well-being, reverse the trend that began when the Affordable Care Act expanded opportunities for poor and some middle-income people to get affordable coverage.

With health care already a central issue in the 2020 presidential campaigns and a prime voter concern, the fresh evidence that insurance is slipping further out of Americans’ reach can be expected to escalate partisan warring about Americans’ access to affordable coverage.

The uninsured rate rose as well in 2018, marking the first time since 2009 that both the number of Americans without coverage and the rate of uninsurance rose from the year before.

The change was driven primarily by a decrease in public insurance for the poor, with enrollment in Medicaid dropping by 0.7%, the data show. The uninsured rate spiked especially, the findings show, among adults who are Hispanic and foreign-born, with the increase in uninsured among both groups three times the national average. Insurance also dwindled among children who are Hispanic and naturalized citizens.

Health policy experts interpreted those patterns as evidence of a chilling effect from the Trump administration’s efforts to restrict several forms of public assistance, including Medicaid for immigrants seeking to remain in the United States. In addition, the number of low-income Americans on Medicaid tends to decline when the economy expands, as it did last year, while some states have been clamping down on eligibility and following the administration’s urging to impose work requirements in the program.

The new report was part of a series the Census Bureau releases annually on the state of the economy. It also reported Tuesday that the U.S. poverty rate fell last year to its lowest level since 2001. The median U.S. income — the point at which half of U.S. families earn less than this amount, and half earn more — topped $63,000 for the first time, although that is roughly the same in inflation-adjusted terms as middle-class income was in 1999.

The Census Bureau painted a picture of an economy pulled in different directions, with a falling poverty rate but high inequality, on top of the growing cadre of people at financial risk because they do not have health coverage.

Health insurance has long been recognized as crucial to people’s ability to get medical care when they need it. The availability of insurance is influenced by a variety of factors, including economic conditions, because most insured U.S. residents get their health plans through an employer. In recent years, however, both supporters and opponents of the ACA have looked at Census’ yearly insurance data as a portrait of how well the law is working.

Expanding access to insurance was a main goal of the ACA, the statute forged by Democrats nearly a decade ago that has reshaped much of the health care system. President Donald Trump and other Republicans contend the law is fatally flawed, while Democrats maintain it has been undermined by recent GOP policies.

As Trump works to dismantle the law and liberal Democratic candidates seek to replace it with a government-financed health-care system, both sides can find ammunition for their interpretation of why the nation’s uninsured rate has started rising again.

Republicans can point to how, as premiums escalate, fewer people buy health plans through the ACA’s marketplaces unless they qualify for federal subsidies. Democrats can point to how major tax changes, adopted by a Republican Congress at the end of 2017, eliminated the financial penalty for those who violate the ACA’s requirement that most Americans carry health insurance – removing one motivation to stay insured.

A consistent decline in the number of uninsured Americans that began in 2011 actually stopped in 2017, according to census data, with about 400,000 more people than in 2016 reporting that they lacked coverage. But that did not amount to a statistically significant change in the uninsured rate.

The new figures for 2018 show that the uninsured rate increased to 8.5% of the population from 7.9% the year before. Both years cover the U.S. population from birth to age 64, just before people become eligible for the federal Medicare program for older Americans.

In contrast, some 9 million Americans gained coverage between 2013 and 2014, the year that Medicaid expanded in many states and ACA insurance marketplaces opened for individuals and families that cannot get an affordable health plan through a job.

Tuesday’s data make clear that the contraction of insurance has been broad. Around the country, insurance coverage worsened in eight states and improved in three states.

For the first time, the Census Bureau breaks out the proportion of Americans buying health plans through the ACA’s insurance marketplaces. They show that 3.3% of people last year got their coverage through such a marketplace. The breakout reinforces how the ACA’s health plans, while attracting considerable political attention, account for only a fraction of the nation’s health insurance.

While Medicaid enrollment fell, the proportion of Americans covered through employer-based insurance did not change significantly. Meanwhile, enrollment in Medicare, the program for elderly and disabled people, expanded slightly – probably as a result of the nation’s expanding population of older residents, Census officials said in releasing the data.

The Bureau’s Current Population Survey is widely regarded as the most reliable portrayal of health insurance in the United States, but there have been other clues the ranks of the uninsured are swelling. In July, the U.S. Centers for Disease Control and Prevention issued findings from the National Health Interview Survey that the number of Americans uninsured at the same they were asked increased from 28.9 million in 2017 to 30 million last year.

The Census’ CPS counts people as uninsured if they lacked coverage throughout the year.

The official U.S. poverty rate fell to 11.8% in 2018, the lowest since 11.7% in 2001 and a sign that the devastation from the Great Recession had faded. Businesses have been hiring minority and low-skilled workers at unusually high rates lately, helping give jobs and opportunities to Americans who struggled for years to get a chance.

The fall in the poverty rate is coming as more people get jobs and move from part-time to full-time work, helping boost incomes. Last year alone, 2.7 million people found jobs, according to the Labor Department.

“We have found quite a big increase in full-time, year-round work that would tend to bring up incomes for working people,” said Trudi Renwick, assistant division chief at the U.S. Census Bureau.