"If the question is do I want or need Rahm Emanuel's support for president, with all due respect to the mayor, no, I don't," the Democratic presidential candidate said at a press conference in Chicago.
The Vermont senator has, in fits and starts, talked up the issue of police brutality in his White House bid. Like Democratic rivals Hillary Clinton and Martin O'Malley, Sanders has faced pressure from the Black Lives Matter movement and others to make it a focal point of his campaign.
Sanders has repeatedly called for the resignation of all Chicago leaders who were involved with keeping hidden a tape of 16-year-old Laquan McDonald being fatally shot by a police officer.
"Like any other public official, when a police officer breaks the law, that officer must be held accountable," said Sanders, who earlier this year endorsed Emanuel's mayoral opponent, Jesus Chuy Garcia.
Emanuel has denied rumors that he refused to release the tape to win a second term as mayor.
Amid mounting protests about law enforcement's handling of alleged police abuse cases, Emanuel in October accepted the Chicago police superintendent's resignation.
But some critics have suggested that the embattled mayor should step down as well. Sanders hasn't gone that far in speaking about his former House colleague. But he's come close.
"All of us -- whether we're black, whether we're Latino, whether we're white -- are tired of looking up at the TV and seeing videos of unarmed people, often minorities, being killed," he said.
Sanders, who went to undergrad at the University of Chicago, said he spent his earliest days as an activist with the Congress of Racial Equality fighting against discrimination against black, Latino and poor people.
"Now much has changed over the decades, but unfortunately, some things have not. Institutional racism existed then. Institutional racism exist today," he said. "The criminal justice system was broken then. The criminal justice system remains broken today. And that's the sad reality of where we are as a country."
Sanders said fighting against these issues is one of the most important things he would do if elected president.
"And it will be an enormously high priority for me," he said.