In March 2017, Baldwin was one of 21 senators led by Ed Markey to sign a letter to Senate Majority Leader Mitch McConnell that said that 12% of adult Medicaid beneficiaries had some form or a substance abuse disorder, that one-third of treatment for opioid and other substance use disorders in the United States is financed by Medicaid, and that the American Health Care Act could "very literally translate into a death spiral for those with opioid use disorders" due to inadequate funding, often resulting in individuals abandoning substance use disorder treatment.