But whether the wager brings Obama and his crusade for change any closer to the White House will be decided far from his adoring masses in Denver, and the pundits dispensing instant conventional wisdom.
Historic headlines were already secured at the convention, with Obama becoming the first-ever African American presidential nominee.
So the Illinois senator had several key aims at the start of his speech — to flesh out his unfamiliar biography, show he was tough enough to handle Republicans, and win over voters queasy at the scope of change he is promising.
Often criticized for hiding a lack of specifics behind his spellbinding oratory, Obama on Thursday laid out a thick, and sometimes wordy summary of what he would do as president.
Those hoping for a fluent, inspiring and lofty sermon may have come away disappointed as he trudged through tax policy, climate change remedies, and blueprints for health and education fixes.
The Illinois senator also seemed intent on protecting his flanks, with Republicans set on Monday to open their convention in Minnesota to nominate John McCain, and sure to send a barrage of bile his way.
"I think he focused heavily on both attacking McCain and the Republicans and tried to anticipate their attacks and to respond to them preemptively," said Costas Panagopoulos, a political science professor at Fordham University.
As he tried to make that elusive link with blue-collar, mainly white Democrats who have disdained him so far, Obama spoke of watching his mother die of cancer and his own itinerant upbringing.
He related the heartrending tales of loss and poverty he had heard from voters on the campaign trail, lashing McCain for claiming he is vain and motivated by personal fame.
"I don’t know what kind of lives John McCain thinks that celebrities lead, but this has been mine.
"These are my heroes, theirs are the stories that have shaped me. And it is on their behalf that I intend to win this election and keep our promise alive as president of the United States."
Julian Zelizer, professor of history at Princeton University, said that while Obama’s speech was a "good start" at capturing the millions of primary voters who backed Hillary Clinton, Obama still had work to do to beat McCain.
"I don’t think that speech would have swayed the people who are on the fence with him," Zelizer said.
"One of the most powerful speeches for that, was the speech that Hillary Clinton gave herself."
Clinton, after fighting a bitter primary campaign against Obama, threw her support behind Obama on Tuesday, and ordered her army of 18 millon voters to follow suit.
Her husband, former president Bill Clinton, on Wednesday followed her exampled telling Democrats Obama was "ready" to be president despite Republican barbs.
The most closely watched opinion polls in the next few weeks will be those which assess feeling among Clinton voters.
Several surveys last week suggested that while just over half had transferred their allegiance to Obama, around one in five were wavering, and others were looking to McCain in November’s election.
Obama’s decision to buck tradition and take the convention out to a sports arena was a risk because Republicans have been portraying him as the "world’s biggest celebrity" out of touch with normal Americans.
But the tableau of tens of thousands of Americans waving the Stars and Stripes made it much harder for his opponents to portray him as unpatriotic, and made a compelling television picture that McCain will struggle to match.