Medicare for All is no longer just a left-wing pipe dream. With polling increasingly in its favor and a record number of Democratic senators and representatives onboard, the idea of expanding Medicare—a government health insurance program for people 65 and older—to all Americans seems like a viable proposal. The case for it was bolstered recently, albeit inadvertently, by a working paper last month from the libertarian, Koch-funded Mercatus Center, which concluded that Senator Bernie Sanders’s plan would save the American public more than $2 trillion over a ten year period.

The paper’s author, senior researcher Charles Blahous, hadn’t meant for that to be the takeaway from the paper, and has repeatedly disputed the $2 trillion figure. Thus began a debate, which is still raging, among partisans and journalists about how to accurately characterize the study. The details and scale of this debate may presage the obstacles Medicare for All will face as its backers seek to make it law.

In a summary of his conclusions, Blahous wrote that Medicare for All would cost the government around $32.6 trillion over its first decade—or $3.26 trillion per year, which is almost exactly how much the government expects to raise in revenue this fiscal year. “Doubling all currently projected federal individual and corporate income tax collections would be insufficient to finance the added federal costs of the plan,” he wrote, adding that it’s “likely that the actual cost of M4A would be substantially greater than these estimates.”

But as Matt Bruenig of People’s Policy Project noticed, a table in the paper shows that while federal spending on health care would increase significantly under Medicare for All, overall health spending—from the federal government, state governments, and private employers combined—would fall by $2 trillion. This is because “the new costs it creates would be more than offset by the new savings it generates through administrative efficiencies and reductions in unit prices.” The headlines in left-of-center media outlets wrote themselves, and Sanders, in a video published on social media, sardonically thanked “the Koch Brothers of all people” for sponsoring the study.

Enter the fact-checkers: The Washington Post’s Glenn Kessler awarded Sanders three out of four “Pinocchios” for saying that the study “shows that Medicare for All would save the American people $2 trillion over a 10-year period.” To arrive at his claim, Kessler largely accepted Blahous’s characterization of Sanders’s plan, which estimated that the senator’s version of Medicare for All would cut provider payments by about 40 percent. “That in theory would reduce the country’s overall level of health expenditures by $2 trillion from 2022 to 2031,” Kessler wrote. “But [Blahous] makes clear that it’s a pretty unrealistic assumption.” Kessler thus said Sanders had “cherry-picked” the $2 trillion figure from the paper. Politifact likewise concluded that Sanders “cherry-picked the more flattering of two estimates,” and rated Sanders’s statement “half true.”

Ryan Cooper of The Week took stock of these and other criticisms of the $2 trillion figure, writing on Tuesday, “The fact checker brigade is saying that provider payments will be hard to cut, and therefore Sanders might end up passing something different than his Medicare bill. Therefore he is a liar. But Blahous’s study absolutely, positively does say that the Sanders plan as written will save the American people $2 trillion…. Vague speculation about future political negotiations has nothing whatsoever to do with the facts of the Sanders proposal, nor the empirical contents of the Mercatus study.” Blahous’s 40 percent estimate, which Kessler and Politifact repeated, also might not withstand mathematical scrutiny: Bruenig reverse-engineered Blahous’s own tables and figured the actual cut would be somewhere around 10.6 percent.

Kessler updated his article—he had originally, erroneously included drug companies in a list of providers to face cuts—but not his rating of Sanders’s statement. Meanwhile, in a fact-check video, CNN’s Jake Tapper also accused Sanders of misrepresenting the Mercatus study. “The study’s author says that that $2 trillion drop is not actually his conclusion. He says that’s based on assumptions by Senator Sanders,” Tapper said, echoing Kessler. But as Sanders noted in response, the Medicare for All bill didn’t actually base its calculations on assumptions. Tapper also mischaracterized the senator’s remarks, claiming Sanders said the government would save $2 trillion. In truth, Sanders said “the American people” would save $2 trillion. Tapper rescinded that claim, and CNN has edited the error out of the video.

But Medicare for All’s critics don’t just worry about the proposal’s cost. An August 21 story by Politico said single-payer healthcare has “proved a tough sell” for Democrats in swing districts. “The problem is Medicare for all just isn’t one of those litmus tests for Democratic primary voters,” Democratic strategist John Anzalone told the outlet. (The story goes on to report that Anzalone’s firm campaigned successfully against a single-payer advocate in Iowa.) It is certainly true that a number of single-payer advocates have lost primary and general elections this year—though the same can be said of Democrats who didn’t back Medicare for All or a similar policy. It might also be true that most voters don’t enter the polling booths with Medicare for All in mind. It doesn’t necessarily follow, however, that voters are turned off by Medicare for All, to the degree that support for the policy will cost candidates their general elections. As the Politico piece itself notes, candidates lose races for all kinds of reasons. The uneven showing by Medicare for All supporters does show that the policy isn’t a magic key to winning votes, but most policies can’t lay claim to that sort of power anyway.

Nobody really denies that Medicare for All will be expensive. There’s not even consensus on what Sanders’s plan would actually cost the federal government. As Politifact reported in July 2017, “Kenneth Thorpe, a professor of health policy and management at Emory University, put the cost at $2.4 trillion a year. A team from the Urban Institute put the number at $2.5 trillion a year. The Committee for a Responsible Federal Budget projected $2.8 trillion a year.” An American transition to a single-payer system would almost certainly increase taxes for some Americans—the wealthiest households—and repeal some tax breaks for corporations and homeowners. For these reasons, single-payer will remain a tough sell to wealthy conservatives like the Koch brothers.

It’s less clear that Medicare for All is a non-starter with voters. A poll published Thursday by Reuters found that 85 percent of Democrats support Medicare for All, and that even 52 percent of Republicans do, too. That’s a sharp increase from a Washington Post/Kaiser Family Foundation poll in April that found that just over half of all Americans support a single-payer system; Medicare’s name recognition and popularity perhaps accounts for the difference between these polls. Support also appears to be somewhat conditional on how pollsters describe the policy to voters. “Opposition grew to 61 percent when supporters were told it would ‘give government too much control over health care,’” The Washington Post reported, citing a different Kaiser Family Foundation poll. That’s a bit at odds with a 2017 Associated Press/NORC poll, which found that 60 percent of respondents believe it’s the government’s responsibility to provide healthcare.

But there’s more to politics than polls. Medicare for All would hardly be the first expansion of the welfare state to be deemed a threat to liberty or too costly. “Many of the New Dealers have no concern whatever for individual freedom,” Senator Robert Taft declared in 1939. Franklin Delano Roosevelt’s New Deal was, he added, “absolutely contrary to the whole American theory on which the country was founded and which has actually made it the most prosperous country in the whole world.” Politifact might have rated Taft’s statement half-true. The New Deal indeed represented a departure from the order the Founders thought they had established—an order that granted citizenship only to white male landowners, and preserved the institution of slavery. The American theory evolves, but these evolutions are never inevitable. They are forced, the product of public demands and popular struggle.

The New Deal, as well as Lyndon B. Johnson’s Great Society programs, were sold in moral terms—a lesson for Democrats as they push Medicare for All. While they do have to account for the policy’s costs, and for the difficulty of transitioning the nation’s healthcare system to a single-payer model, debates over funding and electoral viability miss the real point. The question isn’t whether the transition will be easy; it won’t be. The question is whether or not Democrats believe healthcare is a human right.

America doesn’t regard it as such, and it shows. The U.S. is the deadliest developed nation for expectant mothers, a fact researchers attribute in part to a lack of access to preventable health care. Children sell lemonade to pay for family member’s medical procedures. GoFundMe is a graveyard of failed crowdfunding campaigns. Even when Americans have private health insurance, they can face egregiously large, unexpected bills for emergency care—even at in-network hospitals. In May, Vox reported that it had collected 1300 emergency room bills from patients that demonstrate the scale of the problem, which stems from a systemic flaw in our privatized system: A hospital might be in-network, but an emergency room physician might not be. Americans can do everything right—get jobs that provide benefits, pay their premiums, check to see if facilities are in network—and still face insurmountable financial obstacles to care. The research is clear about the consequences. People get sick, and people die, when they don’t get health care.

That’s why Sanders seized on that $2 trillion figure. If even the Mercatus Center concedes that Sanders’s bill, as written, would lower individual health costs for Americans while expanding access to affordable care, then what do Medicare for All’s critics really object to? The idea that all Americans deserve to have health care, and that it should never bankrupt them? It’s not Sanders and other single-payer advocates who have the most explaining to do. It’s those who insist that Medicare for All will be worse than the realities the American people endure today.