Sen. Bernie Sanders’s biggest supporters are criticizing Joe Biden after the democratic socialist endorsed the former vice president.

Sanders’s campaign press secretary, Briahna Joy Gray, and several other surrogates are expressing their displeasure after Sanders endorsed Biden on the presumptive Democratic nominee’s live stream Monday. Gray explained on Twitter shortly after the announcement why she’s not on board.

“With the utmost respect for Bernie Sanders, who is an incredible human being & a genuine inspiration, I don’t endorse Joe Biden,” she told her followers Monday. (RELATED: Bernie Sanders Officially Endorses Joe Biden For President)

She went on to note that Biden does not support any of the big-ticket items underlying Sanders’ unsuccessful campaign.

“I supported Bernie Sanders because he backed ideas like role #MedicareForAll, cancelling ALL student debt, & a wealth tax,” Gray noted. “Biden supports none of those.”

Other left-wing supporters expressed similar sentiments.

“I can hardly believe what I am watching,” Black Lives Matter activist Shaun King wrote in a tweet Monday before suggesting that Biden was reading off of a teleprompter during his livestream conversation with Sanders.

He added: “Never in my life have I seen a leader require a Teleprompter and script TO HAVE A CONVERSATION with someone. It’s insulting. It’s bizarre.”

CNN commentator and former public health official Abdul El-Sayed also weighed in on Sanders endorsement.

“There’s no way around the disappointment that Bernie Sanders won’t be President,” El-Sayed tweeted Monday before explaining why he thinks the coronavirus pandemic changed everything about the Democratic primary.

“Biden’s message was about the past. But going back to ‘normal’ where 1/10 Americans were uninsured, gigs displaced jobs, & action on #climatechange was halting is a NONSTARTER after #COVID showed just how broken ‘normal’ really was for too many,” El-Sayed added.

The comments come as Democrats try to avoid an internal fight between the progressive and moderate wings of the party.

Sanders, for his part, told his followers Monday before the live stream that he was joining Biden on the livestream and would make an announcement.

“We must come together to defeat the most dangerous president in modern history,” the Vermont senator said.

Meanwhile, Rep. Alexandria Ocasio-Cortez noted in a New York Times interview published Monday that she would continue pushing Biden to adopt positions aligned closer to Sanders’s.

“The whole process of coming together should be uncomfortable for everyone involved — that’s how you know it’s working,” she said.

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