President Trump waves after speaking to the March for Life participants from an event in the Rose Garden on Jan. 19. (Jabin Botsford/The Washington Post)

IN HIS first 12 months in office, President Trump has rarely lost an opportunity to divide the nation. In his State of the Union address Tuesday, he has a chance to recast his presidency in terms of harmony rather than disunion. The perfect unifying theme awaits, if only he will embrace it: "dreamers."

With a deadline fast approaching, the dreamers — young undocumented immigrants brought to the United States as children by their parents — face the loss of work permits and protection from deportation. Beginning March 5, their permits are due to expire under the Obama-era Deferred Action for Childhood Arrivals program; unless the process is delayed by judicial order, they will slip back into the shadows of American life at a rate of nearly 1,000 a day.

That's an enormous looming humanitarian tragedy, one triggered by Mr. Trump's decision last fall to terminate DACA. It's also the rare such tragedy that's entirely and almost immediately avoidable, given the right combination of political courage and restraint from Mr. Trump.

Imagine if, in his address to Congress on Tuesday, he clearly proposed a simple, straightforward deal: major new funding for border security, including hundreds of miles of new and upgraded wall on the Mexican border, in return for permanent protections for the dreamers.

Yes, that deal would require some backbone on the president's part, specifically in standing up to the most restrictionist elements of the Republican base. They are demanding a sweeping overhaul of the entire immigration system with the goal of reducing the overall immigrant flow as their price for protecting the dreamers. That is a deal-killer for Democrats, as Mr. Trump knows.

It was Mr. Trump who publicly assured a bipartisan group from Congress this month that he was prepared to take the heat that a compromise on the dreamers would entail. If this isn't the right time to deploy his heat shield, when is?

Along with political courage, the president needs to summon some uncharacteristic restraint. Name-calling and insults aimed across the partisan aisle will not smooth the way toward agreement. Nor will further attacks on immigrant groups whom Mr. Trump has skewered on Twitter and on the hustings, to the delight of some GOP backers.

The sweet spot on a deal involves border security and the wall, to the dismay of many Democrats, and permanent protections for the dreamers, to the distaste of many Republicans. Against those obstacles is the fact that a large majority of the U.S. public would favor such an accord. In a recent Harvard-Harris poll, more than three-quarters of Americans favored a path to citizenship for dreamers, and more than half supported more secure borders.

A deal is within reach. The question is whether Mr. Trump possesses the skill and statesmanship to seal it, and thereby lay claim to a label that has so far eluded him: Unifier.