Even many Democrats are criticizing Sen. Elizabeth Warren for refusing to admit, in plain words, that her Medicare for All plan will require taxes to increase. They’re right to complain. The point could hardly be simpler: All presidential candidates owe voters an honest accounting of what their ideas will cost and how they’ll be paid for.

Up until now, under repeated questioning, Warren has refused to go further than saying that her health plan will lower costs for most Americans, without ever explaining what she means by costs. A program as expensive as this instantly raises the question of affordability in voters’ minds. There’s only one plausible answer: Taxes will have to go up.

Warren’s reluctance to use the word “tax” in the same sentence as “Medicare for All” is not just wrong; it’s bewildering. The idea that voters won’t worry about how to finance the plan unless somebody says “tax” is an insult to their intelligence and a blatant attempt at evasion. As a tactic, it’s risible, and the attacks Warren is facing on the matter only underline its uselessness.

Warren has explicitly endorsed the Medicare for All plan devised by her fellow candidate Sen. Bernie Sanders. He is happy to explain that his plan will cost trillions of dollars, that taxes will rise to pay for it, and that most taxpayers – so he claims – will nonetheless be better off once you consider that they and their employers will no longer pay health insurance premiums. Questionable as his claim may be, he at least acknowledges that expensive public programs have to be paid for. This is surely the minimum that voters are entitled to expect.

Warren’s reticence on the point is all the more jarring given that she’s built her campaign around dozens of detailed commitments. It turns out that she has a plan for everything except how to pay for the single most expensive promise of her or any other campaign. Pressed on the issue, she even manages to make matters worse – explaining, for instance, that estimates of the cost of Medicare for All vary by trillions of dollars (hardly reassuring) and that many “revenue streams” (but never say “taxes”) might be implicated.

The Medicare for All that Sanders and Warren are pitching is a bad idea, and not only because of what it would cost (some $30 trillion over 10 years). It would also throw a large part of the U.S. economy into turmoil and deny tens of millions of Americans the private health insurance they currently have and like. The commitment to genuinely universal health insurance is admirable, but this can be achieved with vastly less disruption and at much lower taxpayer expense by means of a subsidized “public option.” Medicare for All Who Want It makes much better sense.

Sanders is wrong about the best policy, but he should nonetheless be congratulated for his honesty. He says his plan will cost a fortune and that taxpayers will bear the burden. Warren’s refusal to do the same is fooling nobody and reflects badly on her judgment.