Democratic front-runner Barack Obama scored a coup Wednesday in his White House nominating battle against Hillary Clinton by winning the high-profile endorsement of blue-collar champion John Edwards. Edwards, the party's 2004 vice presidential nominee, formally backed the Illinois senator at an exuberant Michigan rally, reinforcing signs of the Democratic establishment closing ranks behind Obama. The announcement punctured Clinton's short-lived boost after her landslide win in Tuesday's West Virginia primary, although the former first lady said she didn't believe in quitting, and would fight on.