Bernie Sanders supporter Michael E. Sparks, 43, of Indianapolis, Ind., sports a Bernie Sanders tattoo as he participates in a rally in front of City Hall during the first day of the Democratic National Convention in Philadelphia on July 25, 2016. (Jabin Botsford/The Washington Post)

As protests go, this one was a doobie.

Democrats gathering here to nominate Hillary Clinton for the presidency had some company: hundreds of Bernie Sanders supporters marching through town, escorted by a 50-foot dirigible in the form of a reefer.

“Berned by the DNC” was the, er, joint declaration printed on the balloon’s side.

The Bernie backers have reason to be fuming. Their man lost a hard-fought race. But on Monday, they let the fire engulf them — and not even Sanders himself could escape the blaze.

“We have got to elect Hillary Clinton and Tim Kaine,” Sanders told his delegates Monday afternoon.

Supporters of Bernie Sanders gathered outside City Hall in Philadelphia on Monday. Most vowed to never vote for Hillary Clinton, despite Sanders's encouragement to do so while speaking a few blocks away. (Alice Li,Jayne Orenstein/The Washington Post)

Incredibly, they began to boo and jeer. The movement leader, no longer controlling his followers, raised his hand for quiet.

“Brothers and sisters!” he urged. “This is the real world that we live in. Trump is a bully and a demagogue.”

The shouts and jeers continued, followed by a chant of “We want Bernie!”

It was just the opening to the Democratic convention that Donald Trump would have wanted. And the Bernie Bros — and a few sisters — weren’t done. They took their hooliganism to the convention floor at the Wells Fargo Center. They booed Sen. Jeanne Shaheen (N.H.) when she mentioned Clinton. They did the same to AFL-CIO chief Richard Trumka and Adriana Espaillat, who hopes to be the first former undocumented immigrant to win a seat in Congress.

They booed Ben Jealous, former NAACP head and a Sanders supporter, when he said it was time to elect Clinton. They booed Rep. Marcia Fudge (Ohio) when she reminded them that “we are all Democrats,” just as they had booed House Democratic leader Nancy Pelosi earlier in the day. They even booed when the Rev. Cynthia Hale, giving the opening benediction, mentioned Clinton’s name.

For a time, they booed most every mention of Clinton’s name. They chanted “Bernie! Bernie!” and even reprised the Republicans’ cheer: “Lock her up!” Outside, they blocked the main road to the convention site and blocked buses carrying delegates — relenting only when thunderstorms and flooding washed them out.

That the Sanders supporters were frustrated is understandable. Clinton and the Democratic Party have given the progressive wing of the party short shrift in favor of an appeal to the political center.

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Sanders and his supporters were tucked into Monday night’s programming, where they shared billing with first lady Michelle Obama and Sen. Elizabeth Warren (Mass.). The staging sent a clear message: The Sanders people would have their say — and then the convention, and the campaign, would move on.

Of more consequence, Clinton, after securing Sanders’s endorsement, chose as her running mate Virginian Tim Kaine, who has a centrist reputation and has been a free-trader.

Then there was the leak of DNC emails, which proved what Sanders had long alleged: The party was working to help Clinton defeat him. Democratic National Committee Chairman Debbie Wasserman Schultz was ousted after the email revelations, but Clinton promptly named her an “honorary chair” of her campaign.

From a strategic perspective, this is probably a mistake. Clinton’s playing down of the progressives in Philadelphia comes from a belief that she can do better among the non-college-educated whites who have been the core of Trump’s support. But her deficit among non-college-educated white voters, about 30 points, isn’t much worse than President Obama and John Kerry did. Rather than making overtures to the shrinking ranks of blue-collar white voters (just over 30 percent of the electorate, down from half in the 1980s) who aren’t likely to be persuaded, Clinton could have used her vice-presidential selection and her convention to boost enthusiasm among progressives.

But no slight by Clinton or the DNC justifies the display Sanders supporters put on Monday.

After the initial outbursts on the floor, Sanders, who would close the night with a generous attempt at unity, pleaded during the afternoon with his supporters by text and email to desist. “Our credibility as a movement will be damaged,” he cautioned, and, “I ask you as a personal courtesy to me to not engage in any kind of protest on the floor.”

The Sanders hooligans backed off — a bit. But when comedian Sarah Silverman, a Sanders backer, came out to urge support for Clinton, there were more boos and chants of “Bernie! Bernie!”

“You’re being ridiculous,” Silverman told them.

They booed Eva Longoria when she mentioned Clinton. A couple of hecklers shouted at Warren (“We trusted you!”) and disrupted her speech with a chant of “Goldman Sachs!” A few in the vicinity of the California delegation even tried to heckle the first lady’s speech but were shushed by the crowd.

Only the soothing tones of Paul Simon seemed to calm the hall. The singer’s selection for the DNC: “Bridge Over Troubled Water.”

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