Washington (CNN) Civil rights leader and former presidential candidate Rev. Jesse Jackson Sr. on Sunday endorsed Sen. Bernie Sanders for the Democratic presidential nomination.

"With the exception of Native Americans, African Americans are the people who are most behind socially and economically in the United States and our needs are not moderate. A people far behind cannot catch up choosing the most moderate path. The most progressive social and economic path gives us the best chance to catch up and Senator Bernie Sanders represents the most progressive path. That's why I choose to endorse him today," Jackson said in a statement.

"The Biden campaign has not reached out to me or asked for my support," he added. "The Sanders campaign has, and they responded to the issues I raised."

The Sanders campaign said Jackson plans to speak alongside the senator at an event in Grand Rapids, Michigan, on Sunday. The state will hold its Democratic primary on Tuesday -- a key state for both former Vice President Joe Biden and the Vermont senator.

Jackson, a longtime civil rights leader and clergyman, launched campaigns for the Democratic presidential nomination in 1983 and 1987. He won Michigan during his presidential bid in 1988 when it was still a caucus.

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