Barbara Boxer minces no words when it comes to describing the people usually known as the Bernie Bros — a subset of Bernie Sanders supporters who hope to take over the Democratic Party and remake it in their image.

“There is so much negative energy; it’s so angry,” says the former four-term Democratic senator from California. “You can be angry about the unfairness in the world. But this becomes a personal, deep-seated anger at anyone who doesn’t say exactly what you want to hear.”

I ran into Boxer earlier this week and got to talking about a superb report in The Times by my colleagues Matt Flegenheimer, Rebecca R. Ruiz and Nellie Bowles: “Bernie Sanders and His Internet Army.” The piece briefly mentions a 2016 incident in which Boxer went to Nevada to try to unify the party after Hillary Clinton defeated Bernie Sanders in the state’s caucus.

Boxer was an early Clinton supporter. But she’s also a liberal lioness and felt sure she could mollify the crowd. “I thought I could get the booing down,” she recalled. “I said: ‘Why are you booing? I’m Bernie’s friend. When you boo me, you’re booing Bernie.’ ”

Things only got worse. The heckling got louder. Someone picked up a chair as if to throw it. “Security whispers in my ear, you’ve got to get off the stage,” Boxer said. “When I left, my heart was pounding. I’d never had that before.”

Boxer’s story is one of the milder ones The Times tells about the Internet trolls. whose goals seem to have less to do with building Sanders up than with hounding and humiliating anyone who stands in their man’s way.

“When Mr. Sanders’s supporters swarm someone online, they often find multiple access points to that person’s life, compiling what can amount to investigative dossiers,” The Times reported. “More commonly, there is a barrage of jabs and threats sometimes framed as jokes. If the target is a woman, and it often is, these insults can veer toward her physical appearance.”

Does this mean Sanders himself supports this kind of behavior? No, and occasionally he tries to disavow it. But not very hard: Last year, he hired as a top aide and speechwriter David Sirota, accurately described by The Atlantic as “his Twitter attack dog.”

Nor does it mean that anything like a majority of Sanders’s supporters support the nastiness carried out in his name. Yet no other Democratic candidate has so many venomous followers — no Biden Brothers or Warren Sisters to return fire with fire. The only real analog in U.S. politics today to the Bernie nasties are the Trump nasties. They resemble each other in ways neither side cares to admit.

The most obvious resemblance is the adulation they bestow on their respective champions, whom they treat less as normal politicians than as saviors who deserve uncritical and uncompromising support.

“Surrender to a leader is not a means to an end but a fulfillment,” the philosopher Eric Hoffer observed in “The True Believer,” a book that remains as relevant in our populist era as it was in the totalitarian one. “Whither they are led is of secondary importance.”

Since it’s the usual destiny of saviors to be persecuted before they’re exalted, the response of their followers often is to persecute back. But persecute whom? In the demonology of most mass movements there is usually a near enemy and a far one, and the near enemy must be dealt with first and hardest. To this day, hard-core Trump supporters reserve their deepest spite for Republican NeverTrump holdouts (“human scum,” according to the president).

Just so with the Bernie Bros, who see more moderate Democrats not as kindred spirits or potential converts but as sellouts, even traitors — the proverbial enemy within. Partly this is about the normal competition for power, in which the show of ideological purity is treated as evidence of moral superiority.

But it also goes to the heart of what the Bernie Bros are really about. As they see it, ordinary civility isn’t a virtue. It’s a ruse by which those with power manipulate and marginalize those without. Democrats like Joe Biden who play by the rules of civility and bipartisanship aren’t just falling prey to the insidious manipulation.

They are perpetrating and legitimizing it. If there is a silver lining here, it’s that the world has long experience with this brand of zealotry. Bernie Sanders may not be one of his own awful Bros, and may condemn their worst excesses.

But there’s no reason to think they’ll lose their influence should he win the White House — just as Trump’s presidency has emboldened and empowered many of his own worst followers.

s this the Democratic Party the Democrats want? They will cast their first votes for president on Monday evening at the party caucuses in Iowa. Now is the moment for second thoughts.

– Bret L. Stephens has been an Opinion columnist with The New York Times since April 2017.

– Bret L. Stephens has been an Opinion columnist with The New York Times since April 2017.