As our colleague David Weigel reported, Democrats have latched onto the catchy idea of “Medicare-for-all” (also known as M4A) as a way of expressing their support for universal health care.

On July 30, the Mercatus Center at George Mason University released a working paper on the 10-year fiscal impact of the Medicare-for-all plan sponsored by Sen. Bernie Sanders (I-Vt.), which would transition everyone in the United States from a mostly employer-provided health system to Medicare over four years. The report was written by Charles Blahous, a former economic adviser to George W. Bush and a public trustee for Social Security and Medicare from 2010 through 2015.

Gillum, the mayor of Tallahassee, was quoted in Weigel’s article as having touted, during a debate, a $2 trillion cost-savings figure that is in the report. Sanders, too, has tweeted about this $2 trillion number, sarcastically thanking the conservative Koch brothers, whose foundation has contributed to Mercatus. “Let me thank the Koch brothers of all people for sponsoring a study that shows that Medicare for All would save the American people $2 trillion over a 10-year period,” Sanders says in a video with the tweet.