Former Democratic party chief Joe Andrew on Thursday said he was switching his support from Hillary Clinton to Obama, and called on Democrats to heal the party's rift in order to stand strong in the November presidential elections.

"Let us come together right now behind an inspiring leader who not only has the audacity to challenge the old divisive politics, but the audacity to make us all hope for a better America," Andrew wrote in a letter to superdelegates.

Andrew, who was appointed the youngest ever chairman of the Democratic National Committee in 1999 by former President Bill Clinton, urged Democrats to unite behind one candidate after Tuesday's crucial endgame presidential primaries in North Carolina and Indiana.

The long, bitter battle for the Democratic nomination was tearing the party apart, he warned, and handing the advantage to Republican apparent nominee John McCain waiting in the wings.

"We are doing his work for him and distracting Americans from the issues that really affect all of our lives," Andrew wrote.