QUICK, NAME a major public policy issue on which overwhelming numbers of Americans are united. Stumped? (Granted, it's a short list.) Here's one answer: allowing "dreamers" — young undocumented immigrants brought to this country as children — to remain in the United States if they pass background checks, go to school and fulfill other basic requirements. In a dozen polls this fall, including one released Tuesday, respondents who favor permitting dreamers to stay in the United States generally outnumber those who would deport them by at least 3-to-1, and often by 4-to-1 or 5-to-1.

The support for dreamers is bipartisan, and it shows up clearly and almost identically in surveys conducted by Fox News and CNN, among other media outlets, including The Post. Despite that, an array of bills that would protect dreamers from deportation, either by granting them a form of legal status or by putting them on short- or long-term pathways to citizenship, remain stalled in Congress.

The legislative inertia is all the more stupefying given the fact that a clear majority of lawmakers in both chambers on Capitol Hill would vote today to grant dreamers legal status or a route to citizenship. Last week, 34 Republicans in the House of Representatives wrote to Speaker Paul D. Ryan (R-Wis.) endorsing a "permanent legislative solution" for the nearly 700,000 immigrants whose protection from deportation, granted by the Obama administration under the Deferred Action for Childhood Arrivals (DACA) program, will lapse starting in March owing to a decision by President Trump. That's more than enough GOP votes to ensure passage of a House bill to address the problem, given overwhelming Democratic support for such a move.

So far, though, Mr. Ryan seems to prefer a strategy of delay, deferral and dithering. He says he wants Congress to address the issue next year, free from the entanglements of other pressing year-end legislative business, including a spending package whose defeat would mean a government shutdown. But to many in Congress, his prescription sounds like a recipe for inaction — and, potentially, the deportation of thousands of dreamers as their DACA permits expire. In the Senate, that has led some Democrats to consider demanding a DACA fix as the price for their support on the spending bill — and avoiding a shutdown.

Why should it come to that? In the House, a bill introduced by Rep. Carlos Curbelo (R-Fla.) and with 34 Republican co-sponsors would set dreamers on a 10-year pathway to citizenship. In the Senate, a measure with three Republican backers would set a 15-year timetable. Why not take a vote — now?

One answer is Mr. Trump, whose ever-shifting stance on extending protections for the dreamers has had a self-neutering effect. In January, citing his "big heart," he said they "shouldn't be very worried," and in September he urged Congress to act to protect them. More recently, under the influence of anti-immigration hard-liners such as Attorney General Jeff Sessions and White House aide Stephen Miller, he has switched to demanding an array of border-security measures, including construction of a wall on the frontier with Mexico, that are deal-killers for Democrats.

The dreamers, it seems, should in fact be very worried by what is happening in Washington. Under the deadline set by Mr. Trump, nearly 1,000 dreamers will lose their protection from deportation each day beginning March 5. At that point, a cohort of youngsters raised in this country will stop being bargaining chips; they will become part of an unfolding American tragedy. Congress should act now to forestall that completely avoidable, and inexcusable, outcome.