Bernie Sanders Urges Booing Supporters to Embrace Hillary Clinton

PHILADELPHIA — Hundreds of supporters of Bernie Sanders drowned out the Vermont senator with boos Monday as he tried to make the case on the first day of the Democratic National Convention that his fans would need to vote for Hillary Clinton in order to defeat Donald J. Trump.

At a meeting filled with Sanders delegates, Mr. Sanders tried to convince those gathered that Mr. Trump, the Republican nominee for president, was dangerous and a threat to the Constitution and that, as a result, they needed to vote for Mrs. Clinton. However, as he made the argument, the crowd shouted over him and chanted, “We want Bernie.”

“We have got to defeat Donald Trump and we have got to elect Hillary Clinton and Tim Kaine,” Mr. Sanders said.

Live From the Democratic National Convention » The leaked emails threaten to undermine unity at the Democratic convention. Bernie Sanders will get his last chance to push his agenda on the big stage. One last time: Michelle Obama begins the handoff from the Obama era.

However, his words were immediately met with loud boos which lasted several seconds even as he tried to continue his speech. The senator then paused and waited for people to quiet down. But as he spoke, many continued to sign loudly and shake their heads.

“This is a real world we live in. Trump is a bully and a demagogue,” Mr. Sanders continued, as some in the crowd continued to boo and voice their displeasure with Mrs. Clinton. “Trump has made bigotry and hatred the cornerstone of his campaign.”

Yet the crowd remained fixed on their support of Mr. Sanders and not on the idea of defeating Mr. Trump. Over and over again they chanted, “We want Bernie. Bernie. Bernie. Bernie.”

The reaction from Mr. Sanders’s supporters was consistent with the anti-Clinton message delivered by demonstrators earlier in the day. Some pro-Sanders protesters took a harder turn on Monday, chanting “Lock her up” in an echo of the message of the Republican National Convention a week earlier, fueled by the resignation of the chairwoman of the Democratic National Committee.

When a truck with the message “Hillary for Prison” cruised by City Hall, where hundreds of Sanders supporters were gathered, several cheered and rushed to pose for pictures. The truck, like an airplane banner with the same message that flew over Cleveland where Republicans met, was sponsored by the pro-Trump website Infowars, which traffics in conspiracy theories.

“She’s crooked as all get out,” said Brianne Colling, of Canton, Mich., who asked friends to take her picture in front of the sign. “All the proof that’s coming out is that she’s stolen this election from Bernie.”

Ilene Cook, an emergency room nurse from Petosky, Mich., said of Mrs. Clinton, “For the first time in my life I will vote Republican to keep her out of office.” She used a vulgarity to refer to the presumptive Democratic nominee that was common among Republican delegates in Cleveland.

Mrs. Clinton’s low marks for honesty in polls have driven the belief by some Sanders supporters that she and the Democratic National Committee interfered with the nominating contest at Mr. Sanders’s expense. Now die-hard “Bernie or Bust” supporters have seized with greater intensity on what they believe are acts of criminality after the resignation of the committee chairwoman, Representative Debbie Wasserman Shultz of Florida, after the disclosure of leaked emails that showed her staff disparaging Mr. Sanders.

Most Sanders supporters have come home to support Mrs. Clinton, polls show, and on Monday, during his speech on the first day of the Democratic convention, Mr. Sanders was expected to again plead for party unity to stop Mr. Trump.

But some segments of his supporters are not mollified, and their language echoes the harshest critiques from Republicans, like Gov. Chris Christie of New Jersey, who elicited roars of “Guilty” while holding a mock indictment of Mrs. Clinton at his party’s convention.

In Philadelphia, a group is planning a mock trial of Mrs. Clinton on Monday.

Not all protesters said Mrs. Clinton should be fitted for prison stripes, as one sign had it. Ethan Cohen, 16, of Worcester, Mass., stood across from City Hall, holding a banner that listed statements about Hillary Clinton’s private email server and wearing a T-shirt that read “Bernie 2016.”

“What we saw with the R.N.C. last week with the ‘Lock her up’ chants, I think it’s going too far,” he said attributing a lot of such sentiments to “party politics, divisions, pure hatred of her.”

As protesters were about to begin a march, a prominent and respected Sanders surrogate, Nina Turner, showed up, apparently to quiet the anti-Clinton passions.

“Republicans got their own problems — don’t bring that nonsense here,” she said when asked about the “Hillary for Prison” message. She urged the crowd to support Democratic candidates and not defect to a third-party alternative. “I want the Senator Sanders supporters to stay in the revolution,” she said. “It isn’t about him. It’s about us.”

She also rebutted protesters who were arguing that Mrs. Clinton’s handling of her emails while secretary of state showed that she was guilty of criminal activity, despite the finding by the F.B.I. director that she was not.

“People might not be happy about that, but where I want to see our energies go toward is holding Democrats and Republicans accountable,” she said.