DENVER, Colorado (CNN) -- The Democratic National Convention wraps up Thursday with Illinois Sen. Barack Obama, the party's presidential nominee, addressing about 75,000 people at Invesco Field at Mile High.

"Obama will communicate the urgency of the moment, highlight the struggles Americans are facing and call on Americans to come together to change the course of our nation," the Democratic National Convention Committee said in a statement.

Obama became the first African-American to lead a major party's ticket for the White House on Wednesday. His rival for the nomination, Sen. Hillary Clinton of New York, interrupted a roll-call vote to ask that he be nominated by acclamation, or voice vote.

It was a carefully choreographed maneuver designed to unite the party after the bitter primary battle between Obama and Clinton.

The convention's theme for Thursday is "Change You Can Believe In," a slogan borrowed from Obama's successful quest for the Democratic nomination. Watch Democrats nominate Obama »

Prominent speakers who are scheduled to address Democrats on Thursday include Gov. Bill Richardson of New Mexico, who competed for the nomination before backing out and endorsing Obama, and Gov. Tim Kaine of Virginia, who was among those mentioned as possibilities to become Obama's running mate.

Former Vice President Al Gore, the party's presidential nominee in 2000, is also scheduled to speak. iReport.com: Planning to watch tonight's speech? Videotape your reaction

In addition, Democrats plan a tribute to the Rev. Martin Luther King Jr., who delivered his famous "I Have a Dream" speech in Washington, D.C., exactly 45 years ago, on August 28, 1963.

Two of King's children, the Rev. Bernice King and Martin Luther King III, plan to participate in the tribute after remarks from Rep. John Lewis of Georgia, who switched his allegiance from Clinton to Obama during the contentious primary contest.

Obama will formally accept his party's presidential nomination in a speech that is scheduled to start at 8 p.m. local time (10 p.m. ET).

It promises to be the main event after a week of rousing speeches at the Pepsi Center in Denver, Colorado, by Democratic heavyweights, including Sen. Edward Kennedy of Massachusetts, who underwent surgery for a brain tumor June 2, and Clinton, who urged her supporters to back Obama.

On Wednesday night, Sen. Joe Biden of Delaware formally accepted the vice presidential nomination and praised Obama as a leader who had been right on a wide range of issues, including Afghanistan.

"On the most important national security issues of our time, John McCain was wrong and Barack Obama has been proven right," he said. Watch Biden's entire speech »

Also on Wednesday, former President Bill Clinton declared Obama "ready to be president of the United States" after months of attacks from his wife's supporters on the Democratic nominee's lack of experience.

The former president himself was among the most outspoken proponents of that line of criticism of Obama. On Wednesday night, however, he reversed himself and pointed out that Republicans had used the same line of attack against him when he first ran for president.

"It didn't work in 1992 because we were on the right side of history," Bill Clinton said. "It won't work in 2008 because Barack Obama is on the right side of history."

The former president said Obama "will lead us away from the division and fear of the last eight years and back to hope." Watch Clinton's entire speech »

During a brief appearance after Biden's speech Wednesday night, Obama said he believed that "change is brought about because ordinary people do extraordinary things."

He said he chose to speak Thursday at Invesco Field at Mile High, which seats 76,000 people, to make sure "everybody who wants to can come. ... I think we will have a great night. I look forward to seeing you there." iReport.com: Are you in Denver? Share sights, sounds

The Republican National Convention is scheduled to start Monday in Minneapolis-St. Paul, Minnesota, but the presumptive Republican nominee, Sen. John McCain of Arizona, may make headlines before then.

Several Republican sources told CNN late Wednesday that McCain has decided on his choice of a running mate. Some suggested that reporters could learn that person's identity as early as Thursday night not long after Obama's acceptance speech.

All About Barack Obama • John McCain • Joseph Biden