MARYLAND'S GUBERNATORIAL contest isn't until next year, but already candidates are promising free lunches — or rather, in the case of Democrat Ben Jealous, free tuition for Marylanders who attend public universities, colleges and community colleges. The political impulse behind the pledge is clear enough; a similar proposal by Sen. Bernie Sanders (I-Vt.) helped super-charge his candidacy in last year's Democratic presidential primaries. As it happens, Mr. Sanders is among those who have endorsed Mr. Jealous, a former NAACP chief, in the Maryland race.

The trouble is that Mr. Jealous's blueprint — though it remains a tossed-off concept rather than a real proposal, since he hasn't explained how he would pay for it — is probably no more affordable or equitable for Maryland than Mr. Sanders's plan was for the United States.

Making a two- or four-year higher education a free entitlement for "every Marylander," as Mr. Jealous's website promises, would blow a Chesapeake Bay-sized hole in the state budget. At a conservative guess, it would cost several hundred million dollars annually — real money, even measured against the state's annual tax-supported budget of $17 billion.

Mr. Jealous said gauzily that slashing the state's prison population might help fund his proposal. Even if that were doable — and some reductions are already underway, with the savings earmarked for helping former inmates re-enter society — it would hardly make a dent in ensuring universal free tuition.

Legislation this year to achieve a far more modest goal — lifting the burden of tuition for more than 40,000 full-time Maryland community college students — would have cost the state well over $60 million annually, which lawmakers in Annapolis deemed unaffordable. Mr. Jealous's approach would be exponentially costlier: It would sweep in more than 92,000 students at far more expensive four-year colleges and universities

It would also amount to a gigantic giveaway for thousands of well-off families whose children might attend the University of Maryland at College Park or other well-regarded four-year institutions in the state. Maryland, ranked at or near first in the nation by median household income, has tens of thousands of households with assets exceeding $1 million, tops in the country. Why divert state resources from K-12 schools, parks or mental-health care to subsidize those affluent families?

Yes, some students do finish college or graduate school under a mountain of debt. But national figures indicate that debt burdens for most students are relatively modest — as of 2012, 44 percent of students at two- and four-year institutions borrow nothing, and, of those who do incur debt, about 3 in 5 borrow less than $20,000. Set against that burden is the fact that four-year degrees confer enormous income-earning advantages on their recipients — on average, some $1 million over a lifetime.

Democrats such as Mr. Jealous are irresponsible to toss out pie-in-the-sky proposals without first doing the math and calculating the equity. They've swapped analysis for red-meat populism, calculating that the party base is too addled by President Trump to care. As political strategy, it's craven; as governance, it would be reckless. Here's hoping other candidates do better.