Obama with his wife Michelle in Denver. (AP)

Denver, Aug. 29: Barack Obama accepted the Democratic Party presidential nomination yesterday, declaring that the “American promise has been threatened” by eight years under President Bush and that John McCain represented a continuation of policies that undermined the nation’s economy and imperiled its standing around the world.

The speech by Senator Obama, in front of an audience of nearly 80,000 people on a warm night in a football stadium refashioned into a vast political stage for television viewers, left little doubt how he intended to press his campaign against McCain this autumn.

In cutting language, and to cheers that echoed across the stadium, he linked McCain to what he described as the “failed presidency of George W. Bush” and — reflecting what has been a central theme of his campaign since he entered the race — “the broken politics in Washington”.

“America, we are better than these last eight years,” he said. “We are a better country than this.”

But Obama went beyond attacking McCain by linking him to Bush and his policies.

In the course of a 42-minute speech that ended with a booming display of fireworks and a shower of confetti, he offered searing and far-reaching attacks on his presumptive Republican opponent, repeatedly portraying him as the face of the old way of politics and failed Republican policies.

He said McCain was out of touch with the problems of everyday Americans. “It’s not because John McCain doesn’t care,” he said. “It’s because John McCain doesn’t get it.”

And he went so far as to attack the presumed strength of McCain’s campaign, national security. “You know, John McCain likes to say that he’ll follow bin Laden to the gates of hell, but he won’t even follow him to the cave where he lives,” he said.

The speech loomed as arguably Obama’s most important of the campaign to date. It was an opportunity to present himself to Americans just now beginning to tune in on this campaign, to make the case against McCain and to offer what many Democrats say he has failed to offer to date: an idea of what he stands for, beyond a promise of change.

To that end, he emphasised what he described as concrete steps he would take to address the anxieties of working-class Americans, promising tax cuts for the middle class and pledging to wean the country from dependence on West Asia oil within 10 years to address high fuel prices.

With the speech, Obama closed out his party’s convention here and prepared for a quick shift of public attention to the Republicans.

He delivered it in a most unconventional setting, becoming the third nominee of a major party in the nation’s history to leave the site of his convention to give his acceptance speech at a stadium.

In this case, it was Invesco Field, set against the Rockies and about a mile from the arena where he had been nominated the night before. His aides chose the stadium to signal a break from typical politics and to permit thousands of his supporters from across the country to hear him speak.

And it came on a night that offered — by the coincidence of scheduling — a reminder of the historic nature of the Obama candidacy: 45 years to the day after the Reverend Martin Luther King Jr. delivered his “I Have a Dream” speech on the Mall in Washington.