ABC News' Sunlen Miller Reports: Former Vice President Al Gore formally endorsed Sen. Barack Obama, D-Il., on stage before 20,000 people at a rally Monday night in Detroit, Michigan.
"The outcome of this election will affect the future of this planet," Gore said at Detroit's Joe Louis Arena. "We've got to have new leadership. Not only a new president, but new policies."
It marked the first time the Democratic heavyweight, Nobel Peace Prize winner, and climate change crusader publicly backed the presumptive Democratic nominee.
Speaking for 15 minutes to the crowd, the 2000 Democratic presidential candidate -- who stayed out of his party's nomination battle between Obama and Sen. Hillary Clinton -- called the primary an "historic contest."
Seeming to take the experience argument and age difference between presumptive Republican nominee Sen. John McCain and Obama head on, Gore -- who was vice president under Bill Clinton for eight years and served as a representative and senator from Tennessee for seven years before that -- argued the length of years in Washington has nothing to do with preparedness.
“Nevertheless, the other party seems to think that age and experience are factors that will work in their favor during this campaign. But our shared experience as a nation tells us otherwise,” Gore said, using John F. Kennedy's 1960 presidential run against Richard Nixon as an example of another time people had similarly questioned a candidates' age and experience.
“I remember when one prominent Republican wondered out loud whether the Democratic nominee, and I quote, ‘really is grown up enough to be president.’ Another used the phrase, quote, ‘naive and inexperienced,’” he said.
Gore said Obama inspires him the same way JFK did. He pointed out Obama’s opposition to the Iraq war in 2002 – and said he was an “eloquent legislator” as a state senator.
Obama had equally flattering words for Gore and his early actions on climate change, telling the audience that he will count on Gore if he becomes president.
“So Washington, which is always the last to hear the news, may not have listened to Al Gore 30 years ago, but America and the world are listening now, and when I am president I will be counting on Al Gore to help me lead the fight to achieve for a clean energy future here in America and around the globe.”
Tonight was Obama’s third visit to Michigan in a month. He told the crowd that he missed the opportunity to campaign there during the primary season due to the Democratic Party's ruling but that he hopes to make up for lost time.
“I know that we didn’t have a chance to come to Michigan the way we should have. But I want everybody to know the Michigan delegation -- they are going to be fully participating in our contention in November. Because we intend to be winning Michigan in November,” Obama said.
Obama told the crowd that his former opponent, Sen. Clinton would be “at the forefront of bringing change in America” and joked about the length of their hard fought campaign.
“Of course nobody told me the primary was going to last 15 months, that was a long primary,” he laughed, “I was planning to run for the '08 election, not the 2012 election."