PHILADELPHIA — Bernie Sanders' supporters booed and interrupted the Vermont senator when he told the crowd of thousands to vote for Hillary Clinton.

"We have got to elect Hillary Clinton president," Sanders said in a rally announcing a new grassroots undertaking. Immediately, boos loudly rained down in the giant ballroom at the Pennsylvania Convention Center.

The boos interrupted Sanders for half a minute as energetic Sanders volunteers and delegates screamed that they wouldn't support Clinton. "Never Her! Never Her!" parts of the crowd chanted.

A few delegates even interrupted him again, chanting, "Take it back! Take it back!"

"Real politics are not that sexy," Sanders said to calm the crowd down.

Some in the crowd even booed Sanders, the candidate they support, as he walked off the stage.

Justin Snider, a Sanders delagate from Texas, said, "I'm for Bernie. I'm not with him on what he said today."

"[Debbie Wasserman-Schultz] has made a negative contribution to the campaign, she's been an insult to American politics the most recent revelations show she was lying and her entire staff was culpable," California delegate Robert Nelson told the Washington Examiner. Nelson sang "ding dong the witch is dead" in response to Wasserman Schultz's ouster.

"Hillary Clinton is her own person, she has to make up her mind about what's going on around her, whether she's going to continue to serve Wall Street," he added. "I do not believe she has s an understanding of what's going on around her. She is an imprisoned countess in an ivory tower and has no idea what's going on in the states, she's out of touch."

"I was booing because I was really disappointed," said Colorado delegate Drew Romano. "It's kind of like seeing Robin Hood stand next to royalty, and it's really disheartening that everything we've been fighting against, that we've been leaning towards is gone. I wouldn't say he's a sellout, but I'm really disappointed."

"In the next few days I'd like to see him continue reforming the Democratic Party, especially the top officials, I don't think it should stop at Wasserman Schultz, we should hold all the top elites responsible for what they've been doing," he continued.

"We're delegates for Bernie. We believe in what Bernie stands for, not what Hillary stands for. So the platforms that apply to Hillary don't align with what Bernie has," said Georgia delegate Andrew Niquette. "I think I can speak for a lot of us in saying that we feel betrayed that he endorsed her."

"I wanna be able to stand behind him and what his ideals and beliefs are," he added. "What I'm hoping is that we stick to doing what Bernie wants us to do. But in terms of voting for Hillary, that's something that will have to be a later judgment, if she is even elected the nominee."

Other Sanders backers were more sanguine. "I was sent here as a Bernie delegate and that I'd take my cues from Bernie, so that's what I'm gonna do," said California delegate Dotty Lemieux. "He said to support Hillary, but he didn't say anything about Tim Kaine. And there are some people who are really hoping that will change."

"What we heard from him today is that we're in the real world," Kit Andrews, a Sanders organizer from Vermont. "She won the election."

Timothy P. Carney, the Washington Examiner's senior political columnist, can be contacted at tcarney@washingtonexaminer.com. His column appears Tuesday and Thursday nights on washingtonexaminer.com.