Former Vice President Al Gore pledged on Monday to do all he could to help Barack Obama win the White House, saying it was crucial the United States has not only a new leader but a new vision for its future.
US Democratic presidential candidate Barack Obama and former US vice president Al Gore wave to the audience during a campaign stop at Joe Louis Arena in Detroit
Mr Gore, one of the most prominent figures in the US Democratic party and known around the world for his push to combat climate change, publicly backed Obama for the first time at a huge rally in Detroit.
He recalled his own presidential bid in 2000 to urge his party to support the Illinois senator in the November election against Republican John McCain.
"Take it from me, elections matter," said Mr Gore, who lost the election to President George W. Bush eight years ago amid a dispute over the vote in Florida. Mr Gore won the popular vote nationwide but Mr Bush emerged the winner after the Supreme Court ruled in his favour on the disputed Florida balloting.
Mr Gore had remained neutral as Mr Obama and former first lady and New York Senator Hillary Clinton battled over their party's nomination.
At the Detroit rally of about 20,000 people, Mr Gore strongly criticised Mr Bush and said McCain's policies were too similar to those of the current president.
Highlighting Mr Bush's decision to invade Iraq in 2003, Mr Gore said he and Obama spoke out publicly against the war in the months leading up to it.
"After eight years of the worst, most serious foreign policy mistakes in the entire history of our nation, we need change," Mr Gore said.