Sanders offers to support Biden if nominated

"Joe Biden is a friend of mine... What Joe has said, he will support me if I win the nomination, I have said I will support him, because we want to beat Trump. That goes without saying," Sanders told supporters.

Sanders, a U.S. senator from Vermont, may need a victory in Michigan to recapture momentum after Biden showed surprising strength in last week's Super Tuesday contests.

Biden, who is seeking to deliver a knockout blow to rival Bernie Sanders on Tuesday as six states vote, received another boost on Monday when former presidential hopeful Cory Booker endorsed his campaign.