Among the abundant ironies of this election cycle, there is this: We are now in the eighth year of the most liberal administration since Lyndon Johnson's. The primary elections reveal a national mood of anxiety, apprehension and anger, in turn reflecting stagnation at home and failure abroad.
Two-thirds of Americans think the country is on the wrong track. Yet after nearly two terms of Barack Obama's corrosively unsuccessful liberalism — both parties have decisively moved left.
Hillary Clinton cannot put away a heretofore marginal, self-declared socialist. He has forced her into leftward genuflections on everything from trade to national health care.
At the same time, Bernie Sanders has created a remarkably resilient insurgency calling for — after Obama, mind you — a political revolution of the left.
The Republicans' ideological about-face is even more pronounced. They've chosen as their leader a nationalist populist who hardly bothers to pretend any allegiance to conservatism.
Indeed, Donald Trump is, like Sanders, running to the left of Clinton on a host of major issues including trade, Wall Street, NATO and interventionism.
It turns out that the ultimate general election question is not where Cruz or Rubio or Kasich supporters are going — almost all seem to be making their tortuous way to Trump — but where do Bernie Sanders' supporters go?
Most will, of course, go to Hillary. Some will stay home. But Trump is making a not-so-subtle pitch to those Democrats and independents who gave Sanders his victories in the industrial Midwest.
The Trump and Sanders constituencies share one stark characteristic: They are both overwhelmingly white. In the Rust Belt, the appeal is to middle-and working-class voters who have suffered economic and social dislocation.
The question is whether Trump can win a sufficient number of those voters, erstwhile Reagan Democrats, to flip just a few states that, like Michigan and Pennsylvania, have gone Democratic for the last six elections.
Which is why Clinton is treating Sanders so (relatively) gently. She wants to be rid of him but cannot alienate his constituency — especially after the ruckus made by his supporters at the Nevada state convention and after his string of recent victories in West Virginia, Indiana and Oregon and the virtual draw in Kentucky. She needs him.
Normally, endorsements don't matter in American politics. But the Sanders constituency is substantial and very loyal. And rather angry now as they can see the Clinton machine winning the nomination through superdelegates.
She needs his blessing and active support in the general election. If not carefully cultivated and appeased, say, on the party platform and/or vice presidential choice, Sanders could very well disappear after the Philadelphia convention and leave her to her own devices — which are much lacking, as demonstrated in her recent primary losses.
She needs to keep his legions in the game through November. At the very least, she needs him to warn his followers away from a Trump temptation.
That, after all, is Trump's path to victory: Add a few industrial blue states to the traditional must-win swing states — Ohio and Florida, most obviously — and pull off an Electoral College win.
The Clinton counterstrategy is based on the global demographics. Trump's unfavorable numbers are impressive: 79 percent among Hispanics, 73 percent among nonwhites, 72 percent among young people, 64 percent among women, 57 percent in the general population.
Which is the more compelling scenario? Right now, Clinton has the distinct advantage. Flipping reliably Democratic states, as well as lowering Trump's high negatives, are both very difficult.
But there's one wild card: events — unforeseen, unforeseeable, yet near inevitable. We are highly unlikely to go the next six months without a significant crisis.
In September 2008, the financial collapse cemented Obama's victory when he, the novice, reacted far more calmly and steadily than did John McCain, the veteran.
This time around, Trump reacted to the terror attack in San Bernardino with a nakedly nativist, shamelessly demagogic, yet politically shrewd call for (temporarily, allegedly) banning all Muslims from entering the U.S. Roundly denounced by Democrats and leading Republicans alike, Trump watched his poll numbers go through the roof.
Turns out that GOP voters supported the ban, 2 to 1.
A candidate with the tactical acuity to successfully deploy such breathtaking, bigotry-tinged cynicism is not to be trifled with. Under normal circumstances, Clinton wins. But if the fire alarm goes off between now and Election Day, all bets are off. Clinton had better be ready. Trump has shown that he will be.
Charles Krauhammer is a Pulitzer Prize-winning syndicated columnist, published weekly in more than 400 newspapers worldwide. From 2001 to 2006, he served on the president's Council on Bioethics. He is author of The New York Times best-seller "Things That Matter: Three Decades of Passions, Pastimes and Politics." For more of Charles Krauthammer's reports, Go Here Now.