Barack Obama gets down to policy as he wows 80,000 crowd

Barack Obama last night fulfilled the promise of his emergence onto the US political stage four years ago and the dream of Martin Luther King almost half a century ago when he accepted the Democratic presidential nomination before tens of thousands of his supporters.

Obama's address, at Denver's Mile High stadium, put policy flesh on the rhetoric that had helped propel a virtual unknown at the 2004 Democratic convention to within reach of the White House.

Speaking on the 45th anniversary of King's "I have a dream speech", the first African-American to secure the nomination of a major party cast himself as heir to Franklin Roosevelt and John Kennedy.

He brought the 80,000-plus who packed the stadium to their feet when, concluding a 47-minute speech, he paid homage to King. Adopting the cadences of a southern preacher, Obama said it was the promise of America that had brought people from every corner of the country to hear King on the steps of the Lincoln Memorial.

Bush had betrayed that promise during the last eight years and the country could not take the chance of another four under John McCain, Obama said.

Quoting from King's call to march forward together and not turn back, he echoed the father of the civil rights movement: "America, we cannot turn back. Not with so much work to be done … We cannot walk alone. At this moment, in this election, we must pledge once more to march into the future."

After months of criticism that there was no substance behind the dazzling oratory, Obama allied his soaring rhetoric to long passages on how he would deal with America's ailing economy, the biggest election issue. He offered a programme of education, health and energy reforms, allied to job creation and tax cuts.

He finally went after McCain with newfound aggression, to the relief of Democrats despairing at their candidate's unwillingness to go toe-to-toe with his Republican rival. He tied him to Bush, accused him of being out of touch with working- and middle-class Americans, and blamed him for adopting scare tactics and negative campaigning.

Showing that in spite of his lofty rhetoric, he can get down and dirty he made sly digs over McCain's volatile temperament and age: McCain turns 72 today.

To cheers from the crowd, he challenged McCain's foreign policy judgment and rounded on him for supporting the Iraq war at the expense of failing to go after Osama bin Laden in Afghanistan and Pakistan. "John McCain likes to say that he'll follow bin Laden to the Gates of Hell - but he won't even go to the cave where he lives."

The Obama campaign had intended last night's address to be a people's event, a radical change from the insider nature of most conventions that aides said symbolised the grassroots nature of his candidacy. He was only the third Democratic candidate to accept the party's presidential nomination outside a convention hall: Roosevelt did in Chicago in 1932, and Kennedy in Los Angeles in 1960.

Tens of thousands took the chance to be part of last night's event, with long lines snaking for miles around the stadium under a blazing sun and filling the stadium three hours before he spoke.

They came in Martin Luther King t-shirts and in full Obama regalia - t-shirts, hats, and buttons. A few came in Native American traditional dress. One man was dressed as the devil, with smears of red paint on his face and legs.

Vendors sold Obama dolls and life-sized figures of Obama dressed as Uncle Sam.

Inside the stadium, there was a collective sense of history in the making. Flash bulbs popped incessantly from the stands, as people waved small American flags, bopped to Motown and shouted "Yes, we can" as Will.i.am and other performers took to the stage.

Obama came to his first Democratic convention eight years ago short of cash and frequently frisked by security because of his name. Last night he recalled his arrival on the national scene at the next one in when his speech caught the imagination of a despondent Democratic party.

"Four years ago, I stood before you and told you my story - of the brief union between a young man from Kenya and a young woman from Kansas who weren't well-off or well-known, but shared a belief that in America, their son could achieve whatever he put his mind to," he said.

"It is that promise that has always set this country apart - that through hard work and sacrifice, each of us can pursue our individual dreams but still come together as one American family, to ensure that the next generation can pursue their dreams as well."

He used his own life story, too, to address the negative campaign that McCain has mounted over the last two months, in particular that he was too fond of his new-found celebrity status.

He spoke about the sacrifices made by his family. "I don't know what kind of lives John McCain thinks that celebrities lead but this has been mine," he said.

He also responded to charges by Republicans questioning his patriotism. He adapted a line from that 2004 convention speech in Boston to argue that the men and women fighting in Iraq and Afghanistan may have been of different parties but all died under the same flag.

"They have not served a red America or a blue America - they have served the United States of America," he said. "So I've got news for you, John McCain: We all put our country first."

He took McCain to task for his negative campaign ads. "What I will not do is suggest that the senator takes his positions for political purposes," Obama said. "Because one of the things that we have to change in our politics is the idea that people cannot disagree without challenging each other's character and patriotism."