In this fact-checking video, CNN’s Jake Tapper examines claims made by Sen. Bernie Sanders and Democratic congressional candidate Alexandria Ocasio-Cortez about the cost of a “Medicare-for-all” bill that Sanders proposed in 2017.

In a video he shared on Twitter, Sanders said, “Let me thank the Koch brothers, of all people, for sponsoring a study that shows that Medicare for All Act would save the American people $2 trillion over a 10-year period.” Ocasio-Cortez, referring to the same study in a CNN interview, said, “You know in a Koch brothers-funded study … it shows that Medicare-for-all is actually much cheaper than the current system that we pay right now.”

But the author of that report, Charles Blahous, a senior research strategist for the Mercatus Center at George Mason University, said that was not his conclusion. (The Mercatus Center gets some of its funding from the libertarian billionaires, Charles and David Koch.)

A spokesman for Sanders referred to figures not highlighted in the working paper that show that between 2022 and 2031, the currently projected cost of health care expenditures in the U.S. of $59.4 trillion would dip to $57.6 trillion under the “Medicare-for-all” plan. That’s how Sanders figures the study shows $2 trillion in savings over 10 years, but the savings is based on assumptions in the bill that Blahous says are unrealistic.

In the paper’s abstract, Blahous wrote: “It is likely that the actual cost of M4A would be substantially greater than these estimates, which assume significant administrative and drug cost savings under the plan, and also assume that health care providers operating under M4A will be reimbursed at rates more than 40 percent lower than those currently paid by private health insurance.” (“M4A” is short for “Medicare-for-all.”)

An alternative-scenario Blahous included in his paper assumed instead that payments to health care providers would “remain equal on average to the current-law blend of higher private and lower public reimbursement rates.” Under that scenario, there would be a net increase in health care spending.

We explained all of those details in “The Cost of ‘Medicare-for-All,’” which was the basis for this week’s fact-checking collaboration with CNN’s “State of the Union.”

All of our videos, going back to the fall of 2015, can be found on FactCheck.org.