Democratic presidential candidates criticizing Medicare-for-all have taken to chastising Sen. Elizabeth Warren (D-Mass.) for not explaining how she will fund the $30 trillion-plus plan by pointing out that “at least” Sen. Bernie Sanders (I-Vt.) is being honest by conceding the middle class would need to fork over more taxes to pay for it. But now the Medicare-for-all opponents might need another argument.

In an interview with CNBC’s John Harwood, Sanders essentially concedes he cannot — or will not — explain how to pay for it, either. Here is the exchange:

John Harwood: One of the constraints has been fiscal. Senator Warren is producing plans to pay for Medicare-for-all. You’ve identified revenue sources for about half of it. Do you think it’s important to identify revenue sources for the other half? Or do you believe, as those who subscribe to modern monetary theory believe, that we’ve been a little bit too constrained by concerns about the deficit?
Bernie Sanders: We’re trying to pay for the damn thing. At a time of massive income and wealth inequality, it is my view that the wealthiest people in this country, the top 1/10th of 1% should be paying substantially more than they’re paying right now. You have an insane situation. Let my Wall Street friends there tell me why it makes sense. …
John Harwood: But you still have more revenue to go to make it fully paid for, yes?
Bernie Sanders: The fight right now is to get the American people to understand that we’re spending twice as much per capita, that of course, we can pay for it. We’re paying it now in a very reactionary, regressive way. I want to pay for it in a progressive way.
You’re asking me to come up with an exact detailed plan of how every American — how much you’re going to pay more in taxes, how much I’m going to pay. I don’t think I have to do that right now.
John Harwood: You think it’s foolish that Senator Warren is trying to?
Bernie Sanders: I’m not saying it’s foolish. All that I’m saying is that we have laid out a variety of options that are progressive. We’ll have that debate. At the end of the day, we will pay for every nickel of Medicare-for-all, and it will save the overwhelming majority of the American people, who will no longer pay premiums.

In short, Sanders wants to sell Americans on something that covers everyone for everything but not explain how that is possible. That, frankly, is no different that President Trump promising in 2016 that he had a fabulous health-care plan to replace the Affordable Care Act but was not going to share what it was.

I do not see the justification for this sort of politics, which tells voters the only thing standing between them and socialist nirvana is big, bad corporations, when there is no realistic plan to deliver nirvana. Perhaps what is standing between Medicare-for-all and voters is reality.

That brings us back to Warren, who insists she is working on a scheme to pay for the plan that even Sanders cannot pay for. Warren has several options, none of which is ideal but some of which will not sink her candidacy.

First, she can adopt one of the spending schemes put forth by the Committee for a Responsible Budget. (The recommendations include “a 32 percent payroll tax, a 25 percent income surtax, a 42 percent value-added tax, or a public premium averaging $7,500 per capita or more than $12,000 per individual who wouldn’t otherwise be enrolled in Medicare, Medicaid, or [the Children’s Health Insurance Program] … [as well as] more than doubling individual and corporate income tax rates, reducing federal spending by 80 percent, or increasing the national debt by 108 percent of GDP.”) She will need to explain how she keeps her promise to shelter the middle class from higher total costs when "tax increases on high earners, corporations, and the financial sector by themselves could not cover much more than one-third of the cost of Medicare-for-all.” If Warren really believes Medicare-for-all will outweigh the downsides of massive tax increases, then she should be able to make that case.

Second, she can reduce the scope of Medicare-for-all by, say, not adding dental and vision care as Sanders’s plan does, not covering illegal immigrants and not eliminating all co-pays or deductibles. That sort of plan will still cost a whole lot, but perhaps the funding options become more realistic when Medicare-for-all does not include free everything for everyone. (European health-care plans do not provide the gold-plated, extravagant benefits Sanders has adopted in Medicare-for-all.) That still might leave her with an enormous gap in funding.

Third, she can put the transition to Medicare-for-all on a very, very, very slow path. In the past, Warren has suggested intermediate steps such as lowering the Medicare age to 55 or 50, allowing employers to buy in to Medicare or allowing employees to buy in to Medicare. These are reasonable steps that could vastly reduce the costs, but then Warren’s plan would look an awful lot like plans from former vice president Joe Biden, Sen. Kamala D. Harris (D-Calif.) and South Bend, Ind., Mayor Pete Buttigieg. Some of her “You’re just not thinking big enough” language could be thrown back in her face.

Fourth, she can reverse herself and say, “Well, If Sanders isn’t going to say how to pay for it, then I’m not, either.” For an ordinary candidate, that might be a feasible route, but for Warren, who is selling herself as a straight shooter, a departure from phony Washington politicians and a paragon of transparency, this might be the most damaging option of all. Her brand is essentially “honest populism.” Whatever undercuts that and confirms opponents’ accusations that she is slippery, shifty and inauthentic would run the risk of creating even bigger doubts about her candidacy.

Finally, I would add that an honest accounting of Medicare-for-all should also include the impact on jobs. How many insurance company employees would be out of work? How would Medicare-for-all reimbursement rates affect the survival of rural hospitals and the salaries of nurses, technicians and other health-care providers?

In sum, Warren has shown her hand on a range of domestic policy initiatives (e.g., child care, college tuition) and provided a funding mechanism (even if one questions how much the wealth tax will raise). She now has to address the most critical issue for Democratic voters, health care. How she does that could well determine whether she wins the nomination.

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