America, we cannot turn back, not with so much work to be done…

“America, we are better than these last eight years,” Obama said, speaking from an elaborate stage on the floor of the Denver Broncos football stadium. “We are a better country than this.” Fending off Republican attacks on his judgment, experience and ability to understand middle America, Obama insisted it was Arizona Sen. McCain, his GOP rival, who “doesn’t get it.”

“For over two decades, he’s subscribed to that old, discredited Republican philosophy: Give more and more to those with the most and hope that prosperity trickles down to everyone else,” Obama said. “In Washington, they call this the ‘ownership society,’ but what it really means is ‘You’re on your own.’

“Well, it’s time for them to own their failure,” Obama went on, as the stadium erupted in cheers. “It’s time for us to change America.”

In closing out the Democratic convention, the Illinois senator seemed to address any doubts about his readiness for what promises to be a brutal fall campaign. He also sought to answer critics who say that his rhetoric, while perhaps captivating, is often vacant; that his message of hope and change, while inspiring, is platitudinous.

“Let me spell out exactly what that change would mean if I am president,” Obama said.

He pledged “to end this war in Iraq responsibly and finish the fight against Al Qaeda and the Taliban in Afghanistan,” wean the U S from Middle Eastern oil within a decade, cut taxes “for 95% of all working families,” and deliver “affordable, accessible healthcare for every single American.”

Whatever happens in November, Thursday night’s unprecedented scene was a testament to racial progress in America, a nation founded by slave owners and cleaved by civil war followed by a century of acrimony. Less than 50 years ago, people with Obama’s complexion were forbidden from voting in some states.

Far up in the stands, Lionel Washington, 24, passed his hand over his face as if he were in a dream. “I can’t believe I’m here,” said Washington, who is black. “I’m going to cry,” he said when Obama took the stage. “I can’t cry,” he said, as his eyes filled with tears. “Change is gonna come!” he screamed.

Adding to the historical resonance, Obama noted his speech came on the 45th anniversary of Martin Luther King Jr’s ‘I Have a Dream’ address.

“Let freedom ring from the snowcapped Rockies of Colorado!” King said that day; Obama’s triumph, standing in the shadow of those mountains, suggested the country was closer to the colourblind society King saw from the steps of the Lincoln Memorial.

For the most important speech of his political career, Obama chose a setting as audacious as his candidacy itself: a raised blue-carpeted platform at the center the coliseum, with a backdrop of Greco-Tuscan columns and more than a dozen American flags.

When he finished, the sky filled with a blaze of fireworks. His wife, Michelle, and their daughters, Malia and Sasha, joined him on stage along with Biden and Biden’s wife, Jill. The girls danced amid a rain of red, white and blue confetti as flashbulbs winked throughout the stadium.