Bernie Sanders did a strange thing the other day: He apologized to Joe Biden for an op-ed written not by him or his campaign but by a supporter, law professor and anti-corruption crusader Zephyr Teachout.

It wasn’t as though the op-ed was dishonest or outrageous; it accused Biden of being too close to corporate interests and doing their bidding too often, a perfectly legitimate argument to make (whether or not you agree with Teachout’s characterization of that constituting “a big corruption problem” for Biden).

Try to remember the last time you saw any Republican, let alone President Trump, apologize for something that mild that one of their supporters said. Or anything one of their supporters said.

Sanders is operating according to an unspoken rule of our politics: Democrats are responsible for everything their supporters do and say, and also are required to take care not to degrade, disparage or disrespect Republican voters. Republicans, on the other hand, are neither responsible for what their supporters say nor obligated to treat Democratic voters with anything other than contempt.

You probably recall the ungodly amount of criticism Hillary Clinton got for saying in 2016 that “you could put half of Trump’s supporters into what I call the basket of deplorables.” Yet in nearly every presidential campaign, the Republican candidate finds some way to imply or state outright that the people who are voting for them are “real” Americans, while the Democrats’ supporters are something else.

Republicans are also free to make clear their contempt for the places where many Democrats live, whether it’s urban areas or entire states such as California or Massachusetts. But the places where many Republicans live, especially rural areas and small towns, are to be lauded as the wellspring of all that is right and good. Ted Cruz can sneer at “New York values” and get a day or two of criticism, but just imagine the months-long scandal that would ensue if a Democrat asked whether we really wanted to elect someone from Texas.

And you’ll have to imagine it, because any Democrat who said that the people of Cruz’s home state were deficient in some way would never be allowed to live it down, not least because journalists are always ready to scold Democrats for being out of touch with the “heartland.”

This contrast is particularly vivid given who the president is. Even though it would be hard for any Trump supporter to be as horrid a human being as Trump himself, when Clinton said “half” of his supporters were deplorable, she was being generous.

But Trump’s not worried or apologetic. Hatefulness is not a bug of MAGAworld; it’s a feature. It was like pulling teeth to get him to disavow the endorsement of David Duke.

Democrats worry far more about how their supporters reflect on them. That’s why when Sanders apologized to Biden, he may have had on his mind not Teachout but a larger group of his fans: the Bernie Bros.

This is an issue that is probably invisible to most voters but is the topic of extended discussion among activists and journalists: the enthusiasm of some of Sanders’s supporters, particularly the way it expresses itself in online venom against not just his opponents but anyone who defends them. As Scott Bixby of the Daily Beast describes the problem, Sanders is trying to maintain the enthusiasm of his voters “while discouraging a toxic wedge of fandom that threatens to distract from his campaign and turn off potential supporters.”

Clinton made reference to them in a recent interview, lamenting “the culture around” Sanders, “his online Bernie Bros and their relentless attacks on lots of his competitors, particularly the women.” One chief complaint is that when Sanders supporters unleash their displeasure not just at Sanders’s opponents but also at journalists or commentators who criticize him, the social media fusillade has a particularly sexist cast to it.

Sanders has repeatedly told his followers to tone things down and be respectful. It hasn’t worked.

So is it legitimate to vote against someone because you don’t like the people who support them? At a time when political preferences and identity have become so tightly wrapped together, it’s hard to avoid. When we call ourselves Democrats or Republicans, we aren’t just expressing a set of policy preferences; we’re making a statement (to ourselves as much as to others) about what kind of people we are, how we see the world and what we value.

And it’s hard not to think worse of a candidate if his fans are hurling misogynist invective at anyone who criticizes him, even if they constitute only a portion of the people who are voting for him. One critical question is how many of Sanders’s supporters, if he doesn’t win the nomination, will spend the general election attacking the nominee and helping Trump get elected, the way some of them did four years ago.

Now that would be deplorable.

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