Jesse Jackson endorses Bernie Sanders for president

Sen. Bernie Sanders and Jesse Jackson in 2016. (Getty Images)

Sen. Bernie Sanders announced Sunday that civil rights icon Jesse Jackson is formally backing his presidential campaign.

Jackson was set to appear with Sanders during a campaign stop in Grand Rapids, Mich., and planned to say that Biden had not reached out to him for endorsement and Sanders had.

He said he chose Sanders after the senator's campaign offered responses on 13 issues Jackson raised, including protecting voting rights, increasing funding for historically black colleges and universities and committing to putting African Americans on the Supreme Court, according to prepared remarks released by the campaign.

Meanwhile, former Vice President Joe Biden on Sunday received the endorsement of California senator and former Democratic presidential candidate Kamala Harris.

The endorsements come before the next round of primaries, with six states voting Tuesday, including Michigan.