Why are Arizona liberals, Twitter protesting Bernie Sanders?

Bernie Sanders and his supporters face criticism for allegedly using his involvement in the civil rights movement to dismiss questions about how he would handle racism in America as president.

Progressive Democratic candidates Bernie Sanders and Martin O’Malley faced unrest in Phoenix, Ariz., Saturday from “Black Lives Matter” protesters.

The Vermont senator and the former Maryland governor were in Phoenix for what was supposed to be a forum led by interviewer and immigrants rights activist Jose Antonio Vargas at the Netroots Nation progressive convention. Instead, the crowd did most of the talking, demanding as a group that the candidates address police brutality and racism, The Associated Press reported.

For Sen. Sanders, the harsh reception was at odds with his reputation among progressives as a champion of advocacy for the marginalized. CNN reported that “excited supporters” began lining up to secure good seats for the event hours early, but by the end, protesters were walking out on him.

“I’ve been fighting civil rights for 50 years,” Sanders said during the protest, reminding the audience that he had participated in the 1963 march where Martin Luther King, Jr. gave his famous “I Have a Dream” speech. [Editor's note: An earlier version of this story misstated the year of the march and Dr. King's speech.]

But in the eyes of many of the protesters and much of black America, that oft-cited fact is seen less as evidence of dedication to racial justice and more as an attempt at a catch-all shut-down for criticism, comedy podcaster and creator of the hashtag #BernieSoBlack Roderick Morrow told Vox.

“Bernie Sanders, while he does have a good track record on race in the past, he's kind of been avoiding talking about certain racial issues now,” Mr. Morrow said. “Whenever he's asked a question, he goes into a spiel on economics – which is fine, obviously, people do want wage and class equality. But certain issues are race issues, and they do need to be talked about, at least from a candidate that I would like to vote for.”

Morrow said he started the hashtag #BernieSoBlack because he felt supporters used Sanders’ previous civil rights activism to “outblack” black critics.

“I made a joke that's like, ‘Bernie's blacker than us! Bernie's SO BLACK!’” he said. “That's how it feels when they come into our mentions [on Twitter] and tell us that we don't know what we're talking about, and even though [Sanders] doesn't talk about #BlackLivesMatter right now, we should just kind of shut up.”

At the Netroots Nation convention Saturday, Sanders tried giving prepared remarks on economic inequality, but the protesters continued shouting over him. After agreeing that “black lives matter” and referencing his past contributions to civil rights, Sanders threatened to leave, according to CNN.

 "If you don't want me to be here, that's okay. I don't want to outscream people,” he said.

Later that night, Sanders addressed police brutality at an 11,000-person rally. "When a police officer breaks the law, that officer must be held accountable," Sanders said, according to AP.

He also quoted Civil War-era abolitionist and former slave Frederick Douglass, who said, "Freedom doesn't come without struggle."