"Take it from me, if it had ended differently, we would not be bogged down in Iraq, we would have pursued bin Laden until we captured him. We would not be facing a self-inflicted economic crisis; we would be fighting for middle-income families. We would not be showing contempt for the Constitution; we'd be protecting the rights of every American regardless of race, religion, disability, gender or sexual orientation. And we would not be denying the climate crisis; we'd be solving it."
Obama spoke to the crowd on an "in the round," surrounded by the crowd and flanked by columns and a large screen.
The McCain campaign had labeled the stage on which the Democratic contender will speak the "temple of Obama," likening Obama to a rock star and continuing to criticize him as a celebrity rather than a serious candidate for the White House.
Senior Obama campaign officials said the stage is "simple" and "serious" and told ABC News they are not going to apologize for what they called an "enthusiasm gap" between Obama and McCain supporters.
Obama's acceptance speech was moved from the Pepsi Center in Denver, which can accommodate about 20,000 people, to the football stadium earlier this summer.
In a clever political move, the McCain campaign released Thursday night a one-evening-only ad airing on national cable that congratulates Obama on his historic nomination.
"Sen. Obama, this is truly a good day for America," McCain says in the ad. "Too often the achievements of our opponents go unnoticed. So, I wanted to stop and say, congratulations."
"How perfect that your nomination would come on this historic day," McCain continues to say in the ad. "Tomorrow, we'll be back at it. But tonight, senator, job well done."
Obama's campaign said 80,000 people in 48 hours had requested a ticket to Thursday's event and they claim they turned away tens of thousands of people to make space for delegates and other leaders.
A majority of the packed stadium -- 65 percent of the people -- were from the Southwest region including Colorado, Nevada and New Mexico -- states thought to be in play for either Democrats or Republicans in November.
Millions more watched from home and online with Obama scheduled to speak in primetime. Jennifer Hudson sang the national anthem and Sheryl Crow and Stevie Wonder performed.
Viewing the speech as a "persuasion opportunity" to reach out to independent voters in Colorado, the campaign put some of the tens of thousands of people in the stands to work -- calling voters, texting friends -- and training them how to register voters in their area.
Just around 8:00 p.m. ET Obama supporters received this text message: "Final night of convention is tonight -- don't miss Barack's speech! To get involved locally, REPLY: VOL plus your FIRST NAME and TOWN (ex: VOL Ann Chicago)."
Inside the stadium, Denver resident Sandra Bridge, 63, told ABC News, "This is the most exciting period of my life."
"Martin Luther King's dream seemed like it had slipped away," Bridge said. "The dream is real now."
During the convention program, Georgia Congressman John Lewis -- the last living person who spoke at the Martin Luther King, Jr march on Washington, D.C., in 1963 -- introduced a moving video tribute to King, and called the nomination of Barack Obama "a major down payment" on the fulfillment of King's dream.