On Election Day, we cannot, and must not, make the wrong choice.

The Republican candidate is unqualified to be president of the United States.

In two days, we the American people will make our choice in the most momentous presidential election since our predecessors decided three-quarters of a century ago who they trusted to lead them into — and, they prayed, out of — a coming cataclysmic war. We are not at war in 2016; we are not even battling a debilitating economic depression, and yet the comparison between the two elections is not hyperbole. It’s not nakedly partisan politics as usual. The choice we make on Tuesday is as serious as the choice Americans faced in 1940, if not more so.

Those who love this country and that for which it stands — and that number includes friends and allies around the world — can see the looming danger. We cannot, we must not, make the wrong choice.

If this were a normal election — a choice between Bush-Gore, say, or Romney-Obama or even Clinton-Cruz — we would be fighting about issues, for the most part. Policy and programs would be at the forefront; the campaign duels would be about competing visions, the uses of government. The debate would be heated, the campaign tumultuous, probably even dirty, but the fate of the Republic would not be at risk. Donald H. Trump makes it so. The Republican candidate is manifestly unqualified to be president of the United States and temperamentally unfit to be commander in chief and leader of the free world. Even more troubling is his capacity to reshape our nation in ways to make the Founders weep.

If we wake up Wednesday morning with a dangerous demagogue and an enemy of the Constitution on his way to the White House, here’s what we can anticipate:

• Acting either from prideful ignorance or some sort of still-mysterious tie to Russian despot Vladimir Putin, President Trump will begin to cripple NATO, the world’s most important military alliance and a front line of defense against Putin’s expansionist impulses. No wonder our allies are aghast at the prospect of Putin’s “puppet” occupying the Oval Office. This is the man who’ll have his hand on the nuclear button.

• If President Trump and a complicit Congress get their way, we can expect a trade war with China and Mexico. Trump says he’ll label China “a currency manipulator” and seek a 45-percent tariff on Chinese imports. He vows to renegotiate, or more likely withdraw from, the North American Free Trade Agreement and has called for 35-percent tariffs on Mexican imports. China and Mexico will respond by blocking U.S. products, thus igniting a trade war. Inflation will set in, American businesses will lose hundreds of billions of dollars in exports and several million jobs will vanish. We hope that trade-reliant Houston is listening to what he says.

• If President Trump is able to follow through on his trademark campaign promise, he will begin — on Day One, no less — deporting more than 2 million “criminal illegal immigrants” and setting in motion efforts to make life miserable, Sheriff Joe Arpaio-style, for some 11 million men, women and children among us who are undocumented. Ignore for the moment the humanitarian shock to the American system; he’s talking about a process that would disrupt labor markets across the country and that would cost billions of dollars.

And, of course, there’s his multibillion-dollar wall, his brutish border wall slicing through cultures, communities and environmentally sensitive areas of two nations, all to appease a nativist impulse that threatens who we are as a people.

• Trump warns that “Crooked Hillary” is likely to be impeached — and some of his appeasers in Congress echo his warning — and yet a President Trump surely will be distracted by ongoing legal proceedings, including multiple investigations and class-action suits involving Trump’s so-called University. One of those suits is scheduled for trial on Nov. 28 before U.S. District Judge Gonzalo Curiel, the Indiana-born “Mexican” whose integrity Trump insulted. He has threatened to unleash the powers of the presidency against the judge.

• With Donald Trump in the White House, parents, teachers, youth workers and moral leaders will have to avert the eyes of children from a man who has shown contempt for the vulnerable; who has bragged about sexual assault and has made a habit of objectifying women; who lies pathologically; who has promoted racial and ethnic discord; who trades in juvenile name-calling and insult; who has sought to normalize behavior totally unacceptable in places where most of us live and work. One of the enduring mysteries of this election is how millions of conservative Christians are able to rationalize such outrageous behavior.

This editorial page has endorsed Hillary Clinton, enthusiastically. We don’t agree with her on every issue, nor do we excuse her flaws. But we have no doubt that President Hillary Clinton — steady, knowledgable, experienced and sincere — will keep this nation moving forward on a sure and steady course. The intensely partisan battles won’t end — in fact, they’ll probably accelerate — but Americans can be assured that the person we’ve elected president isn’t a threat to the Republic. We can’t say that about her opponent.