Democratic front-runner Barack Obama's White House bid received a fresh momentum on Friday as he secured the support of three more superdelegates, including a former backer of his rival Hillary Clinton. According to an AP tally, the superdelegate count is now Clinton, 271.5, and Obama, 266, a huge shift since the days when the former first lady boasted about a 60-plus lead in the crucial voting bloc. Hillary Clinton is refusing to concede defeat.