Obama is crowned candidate

The 47-year-old senator's meteoric rise to the top of the Democratic Party was sealed last night as delegates voted overwhelmingly to endorse him to fight the election on 4 November.

Hillary Clinton, his former rival for the nomination who gave him a ringing endorsement on Tuesday, helped ensure Mr Obama was chosen unopposed at the party convention in Denver.

As voting began, she asked her New York delegates to support him - then, as hundreds of delegates continued to back her in spite of her releasing them, she took to the stage and called on the convention to nominate their candidate by "acclamation".

"Madame Secretary, I move that the convention suspend the procedural rules and suspend the further conduct of the roll call vote," said Mrs Clinton.

"All votes cast by the delegates will be counted, and I move that Senator Barack Obama of Illinois be selected by this convention by acclamation as the nominee of the Democratic Party of the United States. Barack Obama is our candidate and he will be our president."

The 20,000-strong crowd in the arena roared and chanted "Hillary, Hillary, Hillary." The Democratic Speaker of the House of Representatives, Nancy Pelosi, sought a seconder, to which the delegates collectively responded before a booming "aye" during a voice vote.

Ms Pelosi, chairman of the convention, twice had to offer Mr Obama's response because of the noise from the crowd.

"I have been asked to inform you that Senator Obama accepts the nomination and will deliver his acceptance speech tomorrow night at the fourth night of the convention to be held at Invesco Field," she said.

Mr Obama was at a Denver hotel with his wife, Michelle, and his daughters Maila, 10, and Sasha, seven, and extended family when he learned that he was officially the nominee.

He will deliver his acceptance speech tonight before more than 70,000 people at the Invesco Stadium.

Mr Obama later appeared on the stage after senator Joe Biden had accepted the vice-presidential nomination.

He paid tribute to his 65-year-old running mate, but the biggest cheer came when he saluted Mrs Clinton. "If I'm not mistaken Hillary Clinton brought the house down tonight," he said.

He also thanked former president Bill Clinton, who earlier buried any ill feeling for the man who ended his wife's White House ambitions by saying the senator was "ready to be president".

His acceptance of the nomination will take place on the 45th anniversary of Martin Luther King's "I have a dream" speech. "We are going to have a memorable night," Mr Obama said.

Earlier, Michelle Obama was left wiping away tears as Mr Biden's son, Delaware attorney-general Beau Biden, introduced his father and spoke of hardships his family endured while the elder Biden was in the Senate.

The younger Biden survived a car accident that killed his mother and sister.