Sen. Bernie Sanders addresses delegates Monday at the Pennsylvania Convention Center.
At a raucous rally Monday in Philadelphia, hundreds of delegates to the Democratic National Convention booed their party's presumptive nominee.
The moment of disunity came as Sen. Bernie Sanders (I-Vt.) gave a pre-convention pep talk to an electrified crowd of delegates at the Pennsylvania Convention Center. After celebrating the successes of his insurgent presidential campaign, the senator from Vermont turned his attention to the general election.
"We have got to defeat Donald Trump!" he shouted. "And we have got to elect Hillary Clinton and Tim Kaine!"
The crowd erupted in a chorus of boos that lasted for close to a minute. Sanders raised his right arm in an effort to quiet his most fervent supporters.
"Brothers and sisters," he started. "Brothers and sisters, this is — this is the real world that we live in. Trump is a bully and a demagogue."
As he sought to catalog the many groups the Republican presidential nominee had offended, Sanders was interrupted once more.
"We want Bernie!" members of the crowd chanted. "We want Bernie!"
Sanders tried again.
"Trump is a danger for the future of the country and must be defeated!" he shouted, his voice growing louder. "And I intend to do everything I can to see that he gets defeated!"
Sanders' remarks came hours before he was scheduled to deliver a primetime speech to convention-goers across town at the Wells Fargo Center. His campaign had invited its delegates to the convention center for a morning of workshops and for the pre-convention rally, which featured warm-up speeches from rapper Killer Mike, actress Rosario Dawson and former NAACP president and CEO Ben Jealous.
The senator, who endorsed Clinton two weeks ago in Portsmouth, N.H., did not instruct his delegates on Monday to cast their votes the next night for the presumptive nominee. But he set the stage to do so, arguing that his campaign had made great progress in moving the Democratic Party platform to the left and reforming its presidential nominating process.
"Make no mistake about it: We have made history," he said.
Middlebury College professor Ellen Oxfeld, who served as a Vermont delegate to the convention's credentials committee, said she understood what prompted her fellow Sanderistas to boo the very mention of Clinton.
"A lot of people here — and I guess I include myself — feel that Bernie really would've been the better candidate to defeat Donald Trump," she said.
But Oxfeld said she agreed with Sanders that it was better to vote for Clinton than not.
"I think Bernie made clear that for this political revolution to continue Donald Trump needs to be defeated," she said. "You need the best possible situation to organize and push. And we'd rather be pushing Hillary Clinton than pushing Trump."
Fellow Vermonter Ashley Andreas, a Sanders delegate from White River Junction, said she would have a hard time voting for Clinton on Tuesday night — even if Sanders asked her to.
"We'll see what he has to say, but I don't think I'm going to vote for Hillary Clinton at this convention," she said, accusing the presumptive nominee of acting like a "dictator" and failing to unify the party. "Her approach is off-putting."