Immigration activists protest in the rotunda of the Russell Senate Office Building. (John Moore/Getty Images)

HARPER’S MAGAZINE once published a short story about a small town where everyone knows the exact date of his death yet is powerless to avoid it. That feeling of helplessness, dread and impending doom must be familiar to nearly 700,000 “dreamers” across the country, who need only look at a federal form to ascertain the precise date on which their work permit, and protection from deportation, will be null and void.

For now, a federal court has frozen President Trump’s move to rescind the protections extended to dreamers under the Obama-era program known as Deferred Action for Childhood Arrivals (DACA). That court order could be reversed at any time, however — the Trump administration is doing its utmost to that end. So a blade of uncertainty hangs over the necks of all those young immigrants, brought to this country as children and raised and educated as Americans.

These are the stakes in the debate underway in the Senate, where Majority Leader Mitch McConnell (R-Ky.) has set aside the week for the chamber to devise a solution that has eluded Congress since 2001.

Should Mr. Trump succeed in killing off DACA, as many expect, the human price would be immediate and cruel. On the date the program ends — whether it is March 5, as Mr. Trump wants, or later — roughly 1,000 DACA grantees will lose their protections and work permits every day. That’s 7,000 each week, 30,000 each month, more than 350,000 in the first year, nearly as many the following year.

Overnight, they would lose their ability to earn a living legally, and therefore their jobs, often at workplaces where they are well-established and, given the tight labor market, not easily replaced. If they have health insurance through their employers, that, too, would lapse.

In many states, though not all, dreamers would also lose their driver’s licenses when their DACA permits expired. That would prompt some to continue driving without a license, putting them at enhanced risk of deportation if they happen to be stopped, and others to sell their vehicles — although doing so may be complicated in some places by the fact of their uncertain status.

As for those who are enrolled in public colleges and universities, most, though not all, would be likely to continue receiving in-state tuition as residents of states that have extended that benefit regardless of immigration status to residents who meet other criteria.

But the broader question is: For what future would they be preparing themselves with higher education? And in what way would the United States gain by depriving hundreds of thousands of people, most in their late teens, 20s and early 30s, of any hope of advancement and opportunity? The cruelty is almost matched by the self-destructive folly.

It’s rare that so many lives may hinge so immediately, and so consequentially, on the outcome of any congressional debate. Yet those are the stakes in the Senate’s deliberations this week. It would be good if, along with the political calculations, lawmakers kept sight of them.