PHILADELPHIA, Pennsylvania — Delegates for Sen. Bernie Sanders (I-VT) are complaining about a variety of tactics that they say have been used against them by the Democratic National Committee and the Hillary Clinton campaign to silence them at the Democratic National Convention this week.

Several told Breitbart News on Tuesday evening that 800 Sanders volunteers who had raised funds to participate in the convention were denied access to the floor. Some were relegated to upper-deck viewing areas at the Wells Fargo Center, and some were denied entry altogether.

The accusations were echoed in pro-Sanders forums on reddit and in social media. One Sanders activist, Lisa Barri of New York posted on Facebook: “This has been a very intense day in Philadelphia. 800 Bernie volunteers were not allowed in, stripped of their certifications, and replaced with Hillary volunteers.”

Others told Breitbart News that they had been told they would lose their convention credentials if they protested in favor of Sanders or against Clinton, or if they used signs that had not been approved.

Similar reports were shared among Sanders supporters online: “DNC taking away Bernie signs, threatening no credentials tomorrow if they are loud/hold signs,” one posted on reddit on Monday. Sanders delegates inside the arena were told they could only wave Bernie Sanders signs that had been specifically approved and handed out by the convention staff.

Kevin Hunt, 56, a Sanders delegate from Oregon City, Oregon, told Breitbart News that the roll call vote to nominate Hillary Clinton had been pre-empted by a secret vote early in the day. The purpose: to keep the party’s “superdelegates” from view, lest the public notice that Clinton ended up winning states on the floor that she lost at the ballot box.

“We were given papers to sign, and led to believe we had to,” Hunt said, choking back tears. He also said that telephones at each delegation’s post in the convention hall connected to the Clinton campaign, not to the parliamentarians conducting the vote, and so objections could not be raised. In addition, he said, Sanders delegates who were supposed to lead the roll call for their states were replaced at the last minute by Clinton delegates.

Hunt and others said the convention was just the latest example of voting irregularities in the Democratic primary process, which they said had affected the results in over a dozen states.

“I’ve been a Democrat for 43 years,” he said. “Never before have I experienced this level of illegality, corruption, and cheating — and it only got worse after we arrived in Philadelphia.”

He added: “I don’t view [Clinton] as a legitimate or legally nominated person.”

Another Oregon delegate, Melissa Pancurak, 40, of Portland, said that a convention staffer had spied on their delegation meeting, and had taken photographs of what delegates were texting to each other on their phones before being confronted.

Breitbart News raised some of these accusations with the convention and the Clinton campaign on Wednesday morning.

Clinton spokesperson Brian Fallon said that he had not heard the specific allegations, but that the Clinton campaign had been “working in close coordination with the Sanders campaign to ensure that everybody has an opportunity to be heard,” while “being respectful at the same time.”

He noted that the “floor teams” of the two campaigned had been “merged” on Monday, and observed that “while there was still some chanting going on overall, we had a very unified crowd” on Tuesday.

Sanders supporters had booed speakers who endorsed Clinton on Monday — including Sanders.

“I feel alienated,” said Abby Collins, 45, a delegate from Portland, Oregon. She said the convention staff had used tactics “from the subtle to the egregious” to suppress the voices of the Sanders contingent. She said the process had begun at the state level, and culminated at the convention in Philadelphia, which was stage-managed to promote the party ticket rather than to allow voters a voice.

“They’re professing unity,” she said, “but actions speak louder than words.” She said it had been extremely challenging for Sanders delegates — many of whom had devoted their lives to his cause — to “flip a switch” and support Clinton without being given a chance to express themselves, and to be heard.

Collins and several other Oregon delegates were part of a large walkout — which they called “Demexit” — after the roll call vote concluded on Tuesday evening. Hundreds of Sanders delegates donned gags, held up signs, and raised their fists in silent protest as they left the arena en masse and staged a sit-in inside the media center tent adjacent to the building.

For an hour, speakers onstage at the convention addressed a half-empty hall.

(Clinton spokesman Fallon disagreed: “I think overall in the hall last night you saw a very positive and productive scene and atmosphere.”)

Jeremy Likers, 30, a Sanders delegate from Cornelius, Oregon said that the delegates who walked out had felt silenced twice — first by the DNC and second by the “corporate media,” which was the reason the sit-in targeted the media tent.

But he made sure to come back inside the arena when the protest was over.

“They can’t get rid of us,” he said.

Joel B. Pollak is Senior Editor-at-Large at Breitbart News. His new book, See No Evil: 19 Hard Truths the Left Can’t Handle, is available from Regnery through Amazon. Follow him on Twitter at @joelpollak.

This post has been updated to add information about the replacement of Sanders delegates in the roll call vote.