Bernie Sanders has named Reverend Jesse Jackson Sr. as a special adviser to his campaign. Jackson, who ran for president in 1984 and 1988 and is a prominent civil rights activist, endorsed Sanders in Michigan last weekend.

"I'm humbled and proud to have Rev. Jesse Jackson, Sr. by my side in the fight to expand voting rights, create a single-payer health care system, and finally deliver full social and economic equality for those who have been left behind," Sanders said in a tweet on Saturday.

In a statement last weekend, Jackson said Joe Biden's campaign did not reach out to him or ask for his support. Sanders, to the contrary, did. As mayor of Burlington, Vermont, Sanders backed Jackson in his 1988 presidential campaign, when Biden was also a candidate.

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Jackson said Sanders made several commitments to him, including introducing a constitutional amendment in Congress next week on the right to vote, expanding Pell Grants, nominating an African-American woman to the Supreme Court and naming black women to his cabinet if he is elected president.

The civil rights leader also challenged Sanders to select an African-American woman as his running mate, which Jackson said the senator would give "the highest consideration."

Jackson's support may come too late for Sanders, who has fallen short in several recent primaries. Sanders and Biden are facing off in the first one-on-one debate on Sunday.