The serious problems facing Medicare as it exists now, including insolvency and issues of pricing and care choices described above, will not be lessened by its expansion. But such details are not the focus of the pitch, which offers an attractively simple alternative to our current plight and, crucially, does so by expanding an existing program few meaningfully oppose.

Wouldn’t it be nice to eliminate all this mess of enrollment periods and monthly premiums and switching insurance with every new job and figuring out if the doctor you want to see is in your network? Wouldn’t it be nice to just go get treatment when you need it? And if you don’t object to Medicare for the elderly, why would you object to it for everyone else? That’s the immediately intelligible case for Medicare-for-all or something like it, and when proposed without details on its costs and drawbacks, it has the support of around seven in 10 Americans. If private insurance is not shut down, a federal insurance plan even gets the backing of five in 10 Republicans.

Almost no one likes the insurance system we have now, and the Overton Window on this is shifting rapidly. A mandate for Medicare-for-all may not come from this election, but I don’t expect we’ll close another decade without it.