The speech of Barack Obama's life started with scribbling in a notepad and echoes of previous presidents.

During rare quiet moments on the campaign trail, the Illinois senator jotted down ideas of what he wanted to say at Invesco Field tonight.

He read the acceptance speeches of previous nominees, taking particular interest in three: John F. Kennedy in 1960, Ronald Reagan in 1980 and Bill Clinton in 1992.

Sitting at his computer, Obama knocked out a draft about a week ago and gave it to his speechwriter.

Since then, campaign staff have tweaked the copy.

But when Obama speaks tonight, the words will be largely his own — a personal message to Americans about the choice they will make in November.

"It is now, and probably always will be, that he's the best speechwriter in the group," chief strategist David Axelrod told reporters Wednesday as the candidate traveled to Denver.

"He knows what he wants and he generally says it better than anybody could."

Axelrod wouldn't give specifics about the speech, but said it would outline the "stark differences" between Obama and his rival, Republican Sen. John McCain.

"It's gonna be good," he said.

The speech falls on the 45th anniversary of Martin Luther King Jr.'s "I Have a Dream" speech.

Asked if Obama — the first black presidential nominee of a major political party — would invoke King's speech tonight, Axelrod said only: "We'll see."

Obama is expected to spend much of today running through the speech before taking the stage around 8 p.m. to accept the Democratic nomination for president.

The stadium opens at 1 p.m. to people with credentials. Speeches begin at 5 p.m., with a lineup that includes Gov. Bill Ritter and former Vice President Al Gore.

Obama spent Wednesday morning in Billings, Mont., meeting with veterans and military families on the last stop of a "Battleground States Tour."

On the same day that the Democratic National Convention would include a tribute to military families, Obama told the crowd of about 225 in Billings that he would make it easier for veterans to get the health care they need if he is elected president.

Obama also acknowledged McCain's military service, but said it's not reason alone to send him to the White House.

"We owe him gratitude for that," Obama said. "But we don't owe him our vote. Because the stakes are too high."

Obama arrived in Denver around 3 p.m., shortly before a roll call vote that was cut short and he was nominated by acclamation. He was at his hotel with his wife, Michelle, daughters Sasha and Malia, and extended family, when the nomination was secured.

A few hours later, he made an appearance on the stage of the Pepsi Center as the "special guest" of running mate Joe Biden.

"I think the convention has gone pretty well so far, what do you think?" he asked the crowd.

"We are moving to Mile High Stadium tomorrow," he said. "I look forward to seeing you there."