A decades-old video has emerged showing Chicago cops arresting a young protester — who bears a striking resemblance to young Bernie Sanders — at a 1963 anti-segregation demonstration in Chicago.

The grainy footage could jump-start Sanders’ effort to attract African-American voters ahead of the Feb. 27 primary in South Carolina, where more than half of registered Democrats are black.

Backers of Democratic front-runner Hillary Clinton have questioned Sanders’ history with the civil rights movement.

The video comes from makers of the documentary “‘63 Boycott,” which traces the history of Chicago public schools, with special attention to desegregation protests in August 1963.

Footage shows a protest at the corner of 73rd and Lowe streets, with a young white man in thick glasses, khakis and a sweater being hauled away by cops.

“The man in the video looks like him (Sanders), but we’re not 100 percent sure and we’re working to try to verify it,” an aide to the Vermont senator told The Post on Thursday.

It’s very possible it could be Sanders, who was a student and organizer at the University of Chicago at the time.

A Chicago Tribune article from January 1964 reported that several anti-segregation protesters had been convicted and fined $25 for their roles in demonstrations the previous summer — including a 21-year-old named Bernard Sanders.

Sanders’ birthday is Sept. 8, 1941, so he would have been 21 at the time of the August incident.

Rep. John Lewis (D-Ga.), a civil rights icon and backer of Clinton, has dismissed Sanders’ claims of being a long-time fighter for social justice.

“I never saw him. I never met him,” Lewis scoffed last week at a Congressional Black Caucus event endorsing Clinton.

“I was chair of the Student Nonviolent Coordinating Committee for three years, from 1963 to 1966. I was involved with the sit-ins, the Freedom Rides, the March on Washington, the march from Selma to Montgomery and directed (the) voter education project for six years. But I met Hillary Clinton. I met President (Bill) Clinton.”