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More than 600,000 veterans will go without health insurance next year unless 19 states stop holding out against expanding Medicaid, researchers said Wednesday.

Even with Medicaid expansion, hundreds of thousands of vets are going to go without a way to pay for medical care, the report from the left-leaning Urban Institute finds.

But 327,000 of those who will go without health insurance live in the 19 states -- all with Republican governors -- that have not expanded Medicaid, the researchers said.

It finds more than 120,000 of these fall into the so-called “Medicaid gap” — they are not poor enough to qualify for Medicaid, but they make too much money to qualify for federal subsidies to buy health insurance on the Obamacare exchanges.

And they don’t all get or qualify for care by the Department of Veterans Affairs.

“Some uninsured veterans may qualify for VA care, but not all take up the available coverage or meet the eligibility requirements, which are based on service-connected disability status, veteran discharge status, income, and other factors,” the report reads.

That's still down from 2014, when more than 700,000 veterans went without health insurance, the report found.

“If Medicaid expansion decisions do not change between now and 2017, we project that approximately 604,000 veterans will be uninsured in 2017 and that 54 percent will be living in states that have yet to expand Medicaid,” the Urban Institute report reads.

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Even in states that have expanded Medicaid, 84,000 veterans will fall into the coverage gap, the report found. But there are many more in states that still restrict who can get Medicaid.

"The number of veterans in the assistance gap varies across the selected states, from a projected 8,000 in Virginia to more than 20,000 in Texas and Florida," the report reads.

The 2010 Affordable Care Act was designed to get health insurance to more people in part by creating online exchanges where people could buy health insurance and, often, get federal subsidies to help pay for the premiums.

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It also ended health insurance industry practices that shut many out of care, such as refusing to cover “pre-existing conditions” and capping coverage once people spent a certain amount.

And, it planned to expand Medicaid, the joint state-federal health insurance plan for low-income Americans.

“By mid-2014, 26 states (including Washington, D.C.) had expanded Medicaid, with 32 expanding Medicaid by 2016,” the report reads.

But many Republican-controlled states refused to do it, leaving many of their residents in what’s now called the "Medicaid gap."

The latest Census Bureau data shows it’s worked. The percentage of the U.S. population without health insurance has plummeted from 16 percent in 2010 to 9.1 percent last year. The Health and Human Services Department estimates 20 million Americans gained health insurance coverage between 2010 and 2016.

Veterans have also benefited, the report found.

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“Between 2013 and 2015, the uninsurance rate for nonelderly veterans fell by an estimated 42 percent, declining from 11.9 percent in 2013 to 8.5 percent in 2014, and falling further to 6.8 percent in 2015, according to the National Health Interview Survey,” the team wrote.

“Over this time, veterans also experienced fewer unmet health needs, suggesting that increased coverage translated into improved access to care.”

But that still leaves hundreds of thousands without health insurance.

Related: Obamacare Doesn't Cost More

“There is a tendency to think that all veterans get health coverage through the VA, which is far from the case,” said Kathy Hempstead of the Robert Wood Johnson Foundation, which helped pay for the study.

“While the coverage situation for vets has improved a great deal, hundreds of thousands of veterans remain uninsured, many of whom would be eligible if their states expanded Medicaid.”