Obama seals Democratic nomination

Barack Obama has secured the Democratic nomination and now turns his attention to the task of unifying a fractured party for a five-month battle for the White House with Republican John McCain.

Obama rocketed from political obscurity to become the first black to win the presidential nomination of a major U.S. party. The Illinois senator last night secured the 2,118 delegates he needs for victory at the August convention.

Rival Hillary Clinton, the former first lady who entered the race 17 months ago as a heavy favourite, did not concede and said she would consult with party leaders and supporters to determine her next move.

Obama will be crowned the Democratic nominee at the convention in August and will face McCain in November's election to choose a successor to President George W. Bush.

"Tonight, we mark the end of one historic journey with the beginning of another," Obama told a victory celebration in St. Paul, Minnesota.

"Tonight, I can stand before you and say that I will be the Democratic nominee for president of the United States," he told 17,000 cheering supporters. Another 15,000 gathered outside the arena.

Clinton told New York members of Congress she would be open to becoming Obama's vice presidential running mate, and her backers turned up the pressure on Obama to pick her as his No. 2.