Democratic presidential candidate Bernie Sanders's campaign released this 1988 video showing then-Burlington, Vermont Mayor Sanders endorsing civil rights leader Jesse Jackson for president. (Bernie Sanders)

DEARBORN, Mich. -- With black voters about to play a greater role in picking the next Democratic presidential nominee, Bernie Sanders used a rally here Monday to highlight his support of the 1988 White House run of civil rights leader Jesse Jackson.

Appearing at a rally organized by an auto workers union, Sanders noted that at the time he endorsed Jackson, he was mayor of Burlington, the largest city in Vermont, “a state that is virtually all white.”

“Why did I do it?” the Vermont senator said. “I did it because I saw in him a man trying to bring working people together” and create “a rainbow coalition.”

“It wasn’t a popular thing to do,” Sanders said. “There were three white elected officials in America that endorsed Jackson in 1988. I was one of them.”

Jackson wound up losing the nomination to former Massachusetts governor Michael Dukakis.

After nominating contests in Iowa and New Hampshire -- states that are largely white -- the 2016 Democratic race moves next to Nevada and South Carolina, states with sizable minority populations.

Nevada's Democratic caucus is slated for Feb. 20. The race has emerged as an unusually important test for candidates Hillary Clinton and Bernie Sanders. (Reuters)

Thirty percent of the Democratic electorate in Nevada in 2008 was black or Hispanic, and in South Carolina, 55 percent of the 2008 Democratic electorate was black. In March, another slew of Southern states with large African American populations will vote.

Though Sanders has long been active in the civil rights movement, Clinton started the race far better known among African Americans nationally and enjoys the backing of far more black elected officials than Sanders.

As he continues to try to make inroads with minority voters, Sanders is planning to campaign Tuesday in South Carolina and Georgia.

The senator is scheduled to appear at a morning prayer breakfast in Columbia, S.C., followed by a pair of town hall meetings in Columbia and Charleston. Later in the day, Sanders is scheduled to be joined by the rapper Killer Mike at a forum in Georgia on historically black colleges and universities.