The senator from Vermont is Hillary Clinton’s rival in the contest for the Democratic presidential nomination.

The senator from Vermont has become Hillary Clinton’s chief rival in the contest for the Democratic nomination.

The senator from Vermont has become Hillary Clinton’s chief rival in the contest for the Democratic nomination.

I adore Bernie Sanders.

I agree with his message of fairness and I share his outrage over inequality and corporate abuses. I think his righteous populism has captured the moment perfectly. I respect the uplifting campaign he has run. I admire his authenticity.

And I am convinced Democrats would be insane to nominate him.

Hillary Clinton, by contrast, is a dreary candidate. She has, again, failed to connect with voters. Her policy positions are cautious and uninspiring. Her reflexive secrecy causes a whiff of scandal to follow her everywhere. She seems calculating and phony.

And yet if Democrats hope to hold the presidency in November, they’ll need to hold their noses and nominate Clinton.

Bernie Sanders regularly calls for a "political revolution" in America, but what does that mean? (Peter Stevenson/The Washington Post)

Ultimately, I expect that’s what Democrats will do — because as much as they love Sanders , they loathe Donald Trump more. It seems more evident each day that Republicans have lost their collective reason and are beginning to accept the notion that Trump will be their nominee. And I doubt Democrats will make an anti-immigrant bigot the president by nominating a socialist to run against him.

Sanders and his supporters boast of polls showing him, on average, matching up slightly better against Trump than Clinton does. But those matchups are misleading: Opponents have been attacking and defining Clinton for a quarter- century, but nobody has really gone to work yet on demonizing Sanders.

Watching Sanders at Monday night’s Democratic presidential forum in Des Moines, I imagined how Trump — or another Republican nominee — would disembowel the relatively unknown Vermonter.

The first questioner from the audience asked Sanders to explain why he embraces the “socialist” label and requested that Sanders define it “so that it doesn’t concern the rest of us citizens.”

Sanders, explaining that much of what he proposes is happening in Scandinavia and Germany (a concept that itself alarms Americans who don’t want to be like socialized Europe), answered vaguely: “Creating a government that works for all of us, not just a handful of people on the top — that’s my definition of democratic socialism.”

But that’s not how Republicans will define socialism — and they’ll have the dictionary on their side. They’ll portray Sanders as one who wants the government to own and control major industries and the means of production and distribution of goods. They’ll say he wants to take away private property. That wouldn’t be fair, but it would be easy. Socialists don’t win national elections in the United States .

Sanders on Monday night also admitted he would seek massive tax increases — “one of the biggest tax hikes in history,” as moderator Chris Cuomo put it — to expand Medicare to all. Sanders, this time making a comparison with Britain and France, allowed that “hypothetically, you’re going to pay $5,000 more in taxes,” and declared, “W e will raise taxes, yes we will.” He said this would be offset by lower health-insurance premiums and protested that “it’s demagogic to say, oh, you’re paying more in taxes.”

Well, yes — and Trump is a demagogue.

Sanders also made clear he would be happy to identify Democrats as the party of big government and of wealth redistribution. When Cuomo said Sanders seemed to be saying he would grow government “bigger than ever,” Sanders didn’t quarrel, saying, “P eople want to criticize me, okay,” and “F ine, if that’s the criticism, I accept it.”

Sanders accepts it, but are Democrats ready to accept ownership of socialism, massive tax increases and a dramatic expansion of government? If so, they will lose.

Michael Bloomberg, the billionaire and former New York mayor who floated a trial balloon over the weekend about an independent run, knows this. As t he New York Times reported: “If Republicans were to nominate Mr. Trump or Senator Ted Cruz, a hard-line conservative, and Democrats chose Mr. Sanders, Mr. Bloomberg . . . has told allies he would be likely to run.”

President Obama seems to know this, too — which would explain why he tiptoed beyond his official neutrality to praise Clinton in an interview with Politico’s Glenn Thrush. “I think that what Hillary presents is a recognition that translating values into governance and delivering the goods is ultimately the job of politics,” he said. He portrayed Sanders as “the bright, shiny object that people haven’t seen before.”

It doesn’t speak well of Clinton that, next to her, a 74-year-old guy who has been in politics for four decades is a bright and shiny object. The #feelthebern phenomenon has at least as much to do with Clinton as with Sanders: Democrats are eager for an alternative to her inauthentic politics and cautious policies.

I share their frustration with Clinton. But that doesn’t make Sanders a rational choice.

Twitter: @Milbank

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