Former NAACP head Ben Jealous will endorse Bernie Sanders, a source familiar with the situation confirmed.

The endorsement from Jealous—a popular and prominent civil rights leader—could boost Sanders at a critical time in his primary fight against Hillary Clinton. Sanders has thus far gained most of his support from white progressives and gained little traction among black voters, whose support will be crucial in coming primary states like South Carolina and other southern states.

Jealous was president and CEO of the NAACP for five years starting in 2008 and is now a venture capitalist. He is one of a number of prominent black Americans who have endorsed Sanders, including Dr. Cornel West, rapper Killer Mike, and Ohio state Sen. Nina Turner. Sanders has also attracted support from South Carolina state lawmakers.

Sanders has made criminal justice reform a central part of his platform, and discusses his anti-segregation activism as a college student often on the campaign trail. “We got involved in trying to desegregate the housing owned by the University of Chicago, segregated housing,” Sanders said during a CNN town hall on Wednesday night. “And we also got involved in efforts to desegregate the school system there and I got arrested.”

“But I think, you know, as far back as I can remember,” Sanders added, “but injustice is something that I have always fought throughout my life.”

CNN first reported Jealous’ pending endorsement.

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