By now, we all know that Donald Trump is a loose cannon. He says things he cannot possibly mean in order to whip his national constituency into a frenzy of xenophobia, islamophobia, race hatred, American-firstism and the zeal to depart 11 million to 15 million illegal immigrants.

Every rational person now has to decide whether President Trump would try to fulfill his dark vows. Most of us assume that much of what he has said on the campaign trail will prove to be “mere talk” if he actually becomes the president of the United States. In other words, most people believe that most of his proposals will find it almost impossible to be transformed from high falutin’ rhetoric into any significant changes in American public policy.

By definition Donald Trump is a demagogue.

What bothers me, and it bothers me to the core of my being, is Trump’s willingness to question the legitimacy of our duly elected national leaders and to challenge the legitimacy of our national elections. He can dislike Hillary Clinton all he wants. Fair game. She is a very, very, very imperfect Democratic candidate for the presidency. But he has no right to call into question our marvelous (and somewhat fragile) constitutional order.

For well more than five years, Trump was the chief national spokesman for the Birther Movement — the millions of people who either believe that Barack Obama is not in fact an American citizen or for political advantage pretend to believe that wild and incredibly irresponsible notion. The Birther Movement’s sole purpose was to undermine the legitimacy of a duly-elected American president; to suggest darkly that an Islamist extremist had somehow infiltrated the highest reaches of the American government for the purpose (nobody is quite sure) of overthrowing that government, declaring martial law, installing an Islamic sharia state and undermining the national security of the American people.

Or if all that proves to be “far-fetched,” just to be able to say Obama is “not really one of us.” He’s an African-born imposter who somehow hoodwinked the American people — with the help of their corrupt and liberal media — into electing an alien instead of a good American citizen. In Nebraska, I saw a hand-painted sign at the edge of a ranch: “Don’t blame me, I voted for the American.”

Our democratic republic is a rather fragile constitutional system. It can only perform its function if it rests on a foundation of legitimacy — a widespread, indeed universal, civic agreement that the system is fair, that elections are not rigged, that candidates meet constitutional requirements, that the outgoing president leaves office willingly and peacefully and the incoming president pays respect to his predecessor(s) and the system remains transparent and dedicated to the purposes for which the Founding Fathers intended it.

Legitimacy.

When that legitimacy is called into question, even by a loud minority, the result is national gridlock. In other words, had there been no Birther Movement, our national government might have accomplished quite a bit in the past 7½ years. The Birther Movement had national political implications way beyond its patently moronic foundations and motives.

Trump’s five-year crusade to cast doubt about President Obama’s citizenship, his ability to fuel that doubt with his considerable sums of money and celebrity, casts a large shadow of illegitimacy over the Obama presidency.

Most Americans know better, but Trump’s army of “deplorables” are thrilled when he questions Obama’s citizenship. In fact, long after Trump reluctantly acknowledged that Obama is well, maybe, OK an American, his virulent anti-Obama followers continue to wink at each other as if to say, “We know that Donald knows that Obama is an Islamic plant, whatever he has to say to keep the corrupt media at bay.”

In other words, the message was received for five years, loud and clear, and that message continues to rattle around the perfervid brains of the Trump absolutists. They cannot wait to get one illegitimate person out of the White House. Now they are doing what it takes to de-legitimize Obama’s probable successor.

What could be more irresponsible than to call into question the legitimacy of a duly elected president of the United States? If you are wondering why our system has almost entirely broken down, into the most vicious partisanship and congressional gridlock, into a time when the pool of good will has been drained and cyanide has replaced fresh water, the story begins with a concerted attempt to de-legitimize Obama because he is a: not a conservative Republican; b: a cautious progressie; c: the author of the hated Obamacare; d: someone who has the moral courage to apologize for some of America’s wrong deeds; and e: — O Yes — an African-American, a Negro, a …

Trump’s obsessive Birther street theater is so destructive of the civic norms upon which a working civilization depends, that it essentially qualifies as treason.

Why did he do it? He cheerfully led the Birther Movement to give weight to a wider campaign to de-legitimize President Obama, to help Mitch McConnell and Rush Limbaugh fulfill their vow — stated before Obama took the Oath of Office — to destroy any possibility that he could be an effective President, and to ensure that he would be a one-term president.

Every American should be appalled by what Trump and his army of nihilists have done. We have a set of civic rules in the United States. Candidates are nominated by parties. Elections are held. Elections matter. We need peaceful transfer of power and a very wide general recognition of the legitimacy of the new president, no matter how much you disagree with her or his policies or style. It’s that simple. To lose the election and then call into question the legitimacy of the election and the winning candidate, that is the ultimate form of civic pornography.

Trump should be ashamed. But that is like asking a badger to play checkers. His followers should repudiate him. But as with all demagogic moments in American history, his followers do much of the leading, and Trump just tunes his hateful discourse to amplify their dark views.

You see already that Trump and his minions are planting the seed of an illegitimate election in early November. Trump has told anyone who will listen that the election is “rigged.” Unless he changes course, and lets a teeny in-rush of humility enter his heart, Trump is likely to argue, perhaps during his “concession” speech, that the election was rigged, that irregularities occurred in key battleground states, that the liberal media corrupted the process, that honest citizens were intimidated at the polls, etc. He’s inventive. Stay tuned.

So think of it: Having spent the majority of President Obama’s tenure denying that Obama was the legitimate president of the United States — thus damaging the system, hurting the Obama family personally, making it impossible to get business done in Washington — now Trump spends two years saying he and he alone will have to save the system because nothing gets done in Washington. Think of the irony of that.

Most of the people reading this are wise enough to dismiss the ravings of Trump, especially those about Obama’s legitimacy and the legitimacy of the coming election. But the saddest of sad facts is that many tens of millions of Americans (some of them my friends) either believe that President Obama has been an Islamic “plant” all along or that the coming election will have been no more legitimate than a banana republic’s in 1954. Or both.

So, no matter what happens in three weeks, the dark cloud of illegitimacy will continue to hover over American public life. “Hillary should be in jail.” “The FBI and the Justice Department are in bed with the Clintons.” Etc.

I regard it as little short of treason.

The fracked republic will lurch on, but we deserve better, we deserve so much better.

When Jefferson took over the presidency in 1800, in what he called “The Second American Revolution,” John Adams (bitter and angry) relinquished power with dignity and silence, even though he had serious doubts about his old friend Jefferson’s fitness for the presidency.

Margaret Bayard Smith, observing the inauguration, wrote famous words that should be seared into Donald Trump’s muddled consciousness:  “I have this morning witnessed one of the most interesting scenes a free people can ever witness. The changes of administration, which in every government and every age, have most generally been epochs of confusion, villainy and bloodshed, in this our happy country take place without any species of distraction or disorder.”

We will see if we can get through the next few weeks without villainy, bloodshed, distraction or disorder.