If moderate Democrats are serious when they say their only concern is beating President Donald Trump, they should get used to the thought of backing Sen. Bernie Sanders of Vermont.

If you believe in saving democracy, the courts and the planet, and reversing the unrepentant cruelty, corruption and carelessness that define the current administration, you have a duty to at least consider the candidacy of the most popular senator in America, the top fundraiser in the Democratic primaries, and the man who has generally beaten Trump in head-to-head polls for five years now.

Sure, you can’t ignore a new NBC News/Wall Street Journal poll that shows “socialism”—half of Sanders’ “democratic socialist” brand—about as unpopular as capitalism is popular. Conventional wisdom suggests Republicans would love to run against a socialist as the stock market continually hits new highs, raising all boats that happen to float on a sea of 401(k)s.

But every expert in conventional wisdom has one thing in common: Not one of them has ever beaten Trump.

Democrats can't win without the left

Establishment Democrats seem to live in terror of reliving the 1972 presidential election, when a triangulating Richard Nixon crushed lefty George McGovern. But two much more recent nightmares — 2000 and 2016 — are far more instructive. When Democrats fail to bring their left-most flank into the fold, Republicans are able to swipe elections. Beyond his ability to woo the party’s most reluctant supporters, the best case for the strength of Sanders' candidacy is that pretty much every argument against him ends up pointing to why he might be uniquely electable.

Claims that “nobody likes him” in Washington, or that he can’t overcome his socialist branding, ignore what sets him apart from others. Brian Fallon, former spokesperson for the Hillary Clinton campaign, calls it an “authenticity factor.”

Nobody likes politicians; this is why they play the foil in ad after ad, even in ads for career politicians. Bernie may be a lot of things, but he’s no one’s idea of a Capitol Hill slick.

Yes, Sanders is not a Democrat. Neither are most voters. Independent is the most popular party affiliation in America by far.

Last year, Pete Buttigieg himself made a solid yet obvious point. “If we embrace a conservative agenda, you know what they're going to do?” he said. Republicans will say "we’re a bunch of crazy socialists. So let’s stand up for the right policy, go up there and defend it.”

If every Democrat is going to be called a socialist, maybe the one who has spent decades dealing with this charge is our best choice. And given that 4 in 10 American adults can’t afford a$400 emergency, you can argue that the best candidate to run against Trump—a walking monument to the dangers of inherited wealth—is a candidate who has spent decades warning against the evils of an economy where the top 0.1% own as much as the bottom 90%.

Perhaps the most ridiculous claim is that Bernie hasn’t accomplished enough.

This ignores the more than 200 bills he has co-sponsored that became law—including the 2014 Veterans Access, Choice and Accountability Act he negotiated with conservative lawmakers John McCain and Jeff Miller to reform the Department of Veterans Affairs. (Trump loves that law so much, he often takes credit for it himself.)

And it's practically libelous to disregard Sanders' transformative impact on American politics. He has helped lead the Democratic Party into a renaissance of fighting for big things for working-class Americans. He’s one of the greatest champions of the $15 minimum wage, a movement that has swept many states and helped drive income gains among the poorest workers.

Claims that he promises too much “free stuff” ignore that Democrats have failed when they’ve promised too little.

Supposed big ticket items like free college and universal pre-K might seem overly generous, but they’re just rounding errors compared with the recent increases in the defense budget combined with the massive tax cuts for corporations passed by Trump’s GOP. And while the popularity for "Medicare for All" rises and falls in polls, it would be a strong selling point if the entire Democratic Party got behind it and made the case that it would lead to higher wages.

'Bernie or bust' won't beat Trump

None of this is meant to endorse any sort of hostage-taking “Bernie or bust” mentality.

His followers’ occasional threats to withhold support for their nonpreferred nominee are as unconscionable as they’d be from anyone who should oppose Trump, given the purposeful damage this president gleefully does to the most vulnerable. This spite — along with a sometimes creepy hostility toward “normie” Democrats and a willingness to traffic in conspiratorial thinking that invests mystical sway in a sometimes comically inept Democratic National Committee — offers some evidence that this movement may lack the coalition-building potential necessary to defeat Trump.

But this divisiveness does not often appear in Sanders himself, who has a proven distaste for distractions like Hillary Clinton's “damn emails.”

Like the vast majority of Sanders supporters in the 2016 election, I’d gladly vote for any Democratic nominee over Trump. This senator isn’t even my favorite senator running for the nomination. Yet one reason I have to seriously consider Sanders is that he has the clearest path to uniting the Democratic Party and ousting the evil clown in the Oval Office.

And if you only care about winning, you can’t ignore that.