DENVER (Bloomberg) — Barack Obama was declared the Democratic candidate for president last night, the first black in American history to win the nomination of a major political party.

Hillary Clinton, Obama's former rival, rose on the floor of the Democratic National Convention in Denver yesterday to ask that the roll-call vote be halted and Obama be named by acclamation.

With a roar of cheers and applause, the more than 4,000 delegates at the party's Denver convention shouted "Aye" and formally named the Illinois senator as the party's standard-bearer in the November general election.

Obama, 47, arrived in Denver just a few hours before the delegates began voting. He will give his acceptance speech today before 75,000 supporters in Denver's Invesco Field football stadium, where he'll look to focus the party on defeating Republican John McCain in November.

Clinton earlier yesterday released the more than 1,700 delegates she won during the primaries who were pledged to her, freeing them to cast their ballots for Obama. In a nod to the millions of voters who backed Clinton, her name was placed in nomination as well.