Biden and Sanders win key endorsements as next voting round nears

Democratic presidential hopefuls Joe Biden and Bernie Sanders secured crucial endorsements Sunday from prominent black supporters just days ahead of the first round of voting to pit them in a head-to-head contest.Senator Kamala Harris, a former Democratic candidate herself, endorsed Biden, while Sanders won the backing of civil rights leader Jesse Jackson as the rival candidates competed for African American support -- a key demographic in the fight for the party's nomination.Voters in six state