A frustrated Sen. Bernie Sanders on Friday called on his opponent in the 2020 Democratic presidential primary former Vice President Joe Biden to denounce his surrogate Hilary Rosen after Rosen told Sanders campaign co-chair Nina Turner Thursday night that Turner "didn't have standing" to discuss Martin Luther King, Jr.

"Joe Biden must accept responsibility for his surrogate telling our campaign co-chair Senator Nina Turner that she doesn't have standing to invoke the words of Dr. King," Sanders tweeted. "That is unacceptable and Joe must apologize to Nina and all the people of color supporting our campaign."

Rosen, in a CNN segment with Turner and host Chris Cuomo, said that Turner's invocation of King's famous "Letter From a Birmingham Jail" line about white moderates was imprecise and misinterpreted.

Hilary Rosen thought it was a good idea to lecture QUEEN Nina Turner on Doctor Martin Luther King Jr. pic.twitter.com/8OaDqTCR82 — The Daily Angle (@thedailyangle) March 6, 2020

"You know, Nina referenced Dr. Martin Luther King before saying he said from the Birmingham jail that we should be concerned about white moderates," said Rosen. "That's actually not what Martin Luther King said."

Turner replied by pointing out that it was, in fact, what King had written, and attempted to explain what the quote about the white moderate who prefers peace over justice means before Rosen cut her off, saying that using King's quote "against Joe Biden" was something Turner didn't have standing for.

"Don't tell me what kind of standing I have as a black woman in America," said Turner. "How dare you?"

The back and forth generated commentary on social media and a beleaguered Rosen on Friday tried to clarify her words, telling supporters in a now-deleted tweet that there was no need to defend her "and attack angry black women."

SCROLL TO CONTINUE WITH CONTENT Never Miss a Beat. Get our best delivered to your inbox.





Getting hot reading posts from the USA re: Nina Turner & Hilary Rosen. Hilary displayed as much anger in the interview & pp aren’t referring to “angry white women” like they are referring to “angry black women.” It’s interesting who gets defined by human emotions. Just saying... https://t.co/aHoxSUjYTA pic.twitter.com/aJHyDsF3xe — Bronwyn Fredericks (@BronFredericks) March 6, 2020

"The Biden campaign really needs to reckon with its surrogates' conduct on cable television," said author Brian Abrams. "Millions see this behavior instantaneously."

Sanders and his supporters have been accused for over four years of being uniquely angry and abusive online, an accusation that Biden himself lodged against the Vermont senator in February.

"He may not be responsible for it but he has some accountability," Biden told NBC's Chuck Todd of attacks against political opponents. "If any of my supporters did that, I'd disown them. Flat disown them."

Asked about harassment during a debate in Nevada on February 19, Sanders said that while he condemned anyone attacking people in his name online, Turner and press secretary Briahna Joy-Gray have also been subjected to "vicious, racist, sexist attacks" online and off.

Princeton University professor Keeanga-Yamahtta Taylor, on Twitter, wondered if the standard applied to Sanders and his supporters for their online behavior would be applied to Biden for Rosen's remarks on cable television.

"Gee, wondering if we'll get the same media scrutiny of the surrogates and supporters of other candidates that have regularly heaped abuse on Sanders supporters," said Taylor. "Sanders Is held responsible for the commentary of millions of his supporters. No one else is held to that standard."