Donald Trump will probably lose the election. But he is a final warning. Unless political elites of both the left and the right become more humble, unless they once again ask themselves how their agendas will play in Peoria, the next rough beast might slouch over the corpse of the republic.

"Will it play in Peoria?" goes back to the days of vaudeville. The city of 115,000 in central Illinois was once considered the ultimate focus group, the embodiment of Middle America, the place to test a joke or a soda or a social policy to learn what white folks without a fancy degree thought of it. Back in the day, you knew better than to defy the settled judgment of this ultimate test market. You went as far as Peoria would let you, and no further.

But we grew impatient. You have to fight Jim Crow, whatever Peoria thinks. Free trade will lift most boats, even if it swamps a few. The environment is too precious, and at too much risk, to go slow. Lower taxes and less red tape will help the economy grow, even if it profits some more than others.

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The left wanted social justice, protection for minorities, a cleaner environment. The right wanted lower taxes and trade deals. Despite the rhetoric, each accommodated the other. Republicans left the Democrats' progressive policies largely intact; Democrats learned to embrace, or at least reluctantly accept, globalization.

And everybody knew what was really going on in Washington. A tax break for you. A subsidy for me. You take care of my client and I'll take care of yours. Deal? Then let's celebrate. We'll expense it.

What did the guy on the line think about this? The wife at Wal-mart? The folks at the ball park? No one really cared. Yeah, politicians chased their vote. But respect them, even defer to their collective wisdom? Not so much.

The accommodation between left and right started unravelling in the 1980s. The Bork confirmation. The Thomas confirmation. Contract with America. Impeaching Bill Clinton. Iraq. Obama. The Tea Party. Gay marriage. And now the Democrats want to replace a black president with a woman? A CLINTON?

Meanwhile, Peoria is hurting. The city is home to Caterpillar. But the heavy-equipment giant has outsourced most of its work force overseas or to so-called right-to-work states.

But what does Washington care? The left worries more about combatting global warming than about blue-collar workers with bad backs and no jobs. The right promises to retrain them, but somehow never gets around to it.

The laid-off boys in the bars of Peoria blame the illegals, the only ones even more voiceless than themselves. They seethe at the Wall Street suits who destroyed the economy and got off scot-free. And what the hell is transgender, anyway? They look at their daughter's report card. She's only getting Cs. What future is there for anyone who's only getting Cs?

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I will be your voice, Donald Trump promises. I will get your job back, or at least wreak revenge on the company that gave it away to a guy in Bangladesh. I will send the Mexicans back and keep the Muslims out and build a wall around our country. And you'll have a man, a real man, a white man, your kind of guy, in the White House. We'll be back in charge, folks, you and me. It'll be great again. And they'll never take it away from us.

There are probably enough people left who understand that this is a lie to keep Donald Trump from becoming president. But this is last-chance time. And not just for America, for all of us.

The rage that created Donald Trump voted for Brexit and is wreaking havoc on the continent. It's Marine Le Pen in France and Norbert Hofer in Austria. It's the Law and Justice party in Poland and Jobbik in Hungary and Alternative for Germany.

Read more: Munich, Nice, Turkey, Brexit, Trump — it's all connected

Don't be smug. In politics, Canada is often the United States, only five years behind. We must heal this breach. It's getting serious, now. The next Congress and the next U.S. administration must reach out to each other. They don't have to get all kumbaya about it, but Americans of all persuasions can surely find ways to bring hope to Middle America, to working white America, to the old America that must never be dismissed, even if it is on the wane.

Let's not sign those trade deals until we know which jobs will be at risk and what we can do for those workers. Let's not shut the coal mines without a thought for what will become of the miners. Don't offer amnesty until you have control over the border. As we move to driverless cars and machine learning and an economy in which any action that is repeated can be automated, let's spare a thought for the kids who only get Cs in school. What will become of them? What do you mean you have no idea? That's your job! Let's bring some small measure of consensus back to political culture. Let's bring humility back. Let's go back to asking: Will it play in Peoria? And if it won't, then let's think about that before we push ahead. Because you really, really don't want to see what comes after Donald Trump.