A video from 1987 shows Sen. Bernie Sanders (I., Vt.) has not always considered single-payer health care a slam dunk for progressive reformers.

Sanders said Medicaid for every American "would bankrupt the nation" while he was mayor of Burlington, Vermont, in a clip posted by the NTK Network. Speaking with physician Milton Terris on his local television show "Bernie Speaks with the Community," Sanders discussed the possibility of implementing single-payer health care in the U.S.

"You want to guarantee that all people have access to health care as you do in Canada," Sanders said.

"But I think what we understand is that unless we change the funding system and the control mechanism in this country to do that—for example, if we expanded Medicaid [to] everybody," Sanders added. "Give everybody a Medicaid card—we would be spending such an astronomical sum of money that, you know, we would bankrupt the nation."

But Sanders is now pushing basically the same idea with his Medicare-for-all proposal that has become a cause célèbre on the progressive left.

Sanders claims his bill would solve that problem by giving the government power to negotiate prices, but many experts consider his estimates highly optimistic. A study by the Urban Institute suggested that Sanders’ campaign plan would cost $32 trillion over 10 years, which is about double Sanders’ estimate of the revenue his measures would generate.

"Even with all of those potential revenue-boosters, Sanders may still fall far short of the total amount of money needed to pay for his ambitious program," Danielle Kurtzleben reported at NPR.

Hillary Clinton, Sanders’ opponent in the 2016 Democratic presidential primary, has criticized the senator for previously not knowing how the government would pay for Medicare-for-all.

Sanders has garnered enthusiastic support among some Democratic leaders in the Senate, specifically those considered presidential contenders in 2020. These supporters include Sens. Cory Booker (D., N.J.), Elizabeth Warren (D., Mass.) and Kamala Harris (D., Calif.), although House Minority Leader Nancy Pelosi said it is not a litmus test for Democrats.