The expansion of Medicaid under Obamacare made the opioid epidemic even worse, according to a report commissioned by Sen. Ron Johnson, chairman of the Senate Homeland Security and Governmental Affairs Committee.

The report suggests that because people who were uninsured were able to get government-funded Medicaid coverage under Obamacare, they are now receiving more access to prescription painkillers like OxyContin, and some are selling them illegally on the streets.

"I'm not saying this is a primary cause," Johnson, R-Wis., said in a hearing on the topic Wednesday. "I think what we are certainly saying is this is an unintended consequence. It's certainly a contributing factor. It maybe enables something that shouldn't be enabled. It's a very serious problem that has to be taken a look at."

Johnson has been raising questions about the way Medicaid contributed to the opioid epidemic since last year. His report indicates that at least 1,072 people have been convicted or charged nationwide since 2010 for improperly using Medicaid to obtain prescription opioids, some of which were then resold illegally.

The opioid epidemic began largely because of improper prescribing of narcotic painkillers, and deaths have been rising as people who become addicted switch to street counterparts like heroin, or fentanyl, which is more potent and is often added to drugs without the users' knowledge. At least 42,249 people died from opioid-related deaths in 2016, according to federal mortality data.

Democrats have rejected accusations that Medicaid is contributing to worsening the epidemic. They noted that deaths from overdoses began to increase before the expansion of Medicaid, which started in 2014. Obamacare was originally written to expand Medicaid in all states to anyone who made less than roughly $16,000 a year, but a Supreme Court decision made the provision optional for states.

As a result, data scientists have used differences in state Medicaid programs to demonstrate changes in various health outcomes, given that 18 states haven't yet expanded the program, and Maine is in the process of doing so.

According to the report from Johnson, which used such comparisons, drug overdose deaths per one million people are rising almost twice as fast in expansion states as non-expansion states.

Others disagree about the correlation. One study published in the journal Health Affairs suggested that allegations that Medicaid contributed to the opioid epidemic were not credible, showing a graph that demonstrated deaths from overdoses rose in states that expanded Medicaid as well as in states that did not. One of the authors of the study is Emma Sandoe, who worked for HHS under former President Barack Obama.

Democrats are worried that reports arguing against Medicaid will lead to restrictions on the program, which Republicans have sought to turn into a block grant program that would limit federal spending on it. Democrats note as well that the coverage program, which is used by low-income people, can help them pay for needed treatment for addiction.

​"​Certainly more needs to be done to prevent the over prescription of opioids and hold bad actors accountable, and we should continue to work across the aisle to keep prescriptions out of the wrong hands​," said Sen. Jeanne Shaheen, D-N.H, in a statement provided to the Washington Examiner.​ "However, it’s reckless and, ultimately futile, to try labeling healthcare and treatment access as the problem, rather than what’s desperately needed to turn the tide of this epidemic.”

The Johnson report argued that treatment programs under Medicaid are leading to cost increases. Spending on a single opioid overdose medication, for example, increased 90,205 percent between 2011 and 2016, and costs increased “most notably after 2014.”

Johnson sent his report, “Drugs for Dollars: How Medicaid Helps Fuel the Opioid Epidemic,” to Eric Hargan, acting secretary for the Department of Health and Human Services, and Seema Verma, administrator for the Centers for Medicare and Medicaid Services. He has asked the agencies to detail what they are doing to prevent Medicaid fraud that is related to getting opioids.