"I don't fit the typical pedigree, and I haven't spent my career in the halls of Washington.

"But I stand before you tonight because all across America, something is stirring. What the nay sayers don't understand is that this election has never been about me, its been about you."

"America, we are better than these eight years," Obama said. "We are a better country than this," he said.

"We meet at one of those defining moments -- a moment when our nation is at war, our economy is in turmoil, and the American promise has been threatened once more."

Obama didn't flinch from offering himself as ready not only for the title of president but also of "commander in chief".

"If John McCain wants to have a debate about who has the temperament, and judgment, to serve as the next commander in chief, that's a debate I'm ready to have," Obama said.

Melding his signature line and his rival's convention theme, Obama said the nation's troops "have not served a Red America or a Blue America - they have served the United States of America. So I've got news for you, John McCain. We all put our country first."

Obama delivered his 44-minute speech in a dramatic setting, a filled sports stadium, the camera flashes in the night, the made-for-television backdrop that suggested the White House, and the thousands of convention delegates seated around the podium in an enormous semicircle.

He vowed to end the war in Iraq and to break America's dependence on Middle Eastern oil within a decade.

In addressing the convention, Obama returned to a setting where he became a national star. He was a little-known Illinois state legislator running for the U.S. Senate when he delivered the keynote address at the 2004 Democratic National Convention.

Obama's energy plan would include tapping natural gas reserves, safe use of nuclear power, investments in clean coal technology and a decade-long, 150-billion-dollar program to promote "affordable, renewable sources of energy".

Obama emphasised that more Americans are out of work or "working harder for less", and more have lost their homes and are falling behind on their credit card bills and school tuition payments.

He conceded that not all of the country's problems were Bush's fault, but charged that the government's "failure to respond is a direct result of broken politics in Washington" and of Bush's failures.

"We meet at one of those defining moments - a moment when our nation is at war, our economy is in turmoil, and the American promise has been threatened once more," Obama said.

He was confident that the country would restore its "promise" through the commitments of "ordinary men and women - students and soldiers, farmers and teachers, nurses and janitors."

Obama lashed back at Republicans who say Democrats won't defend the country, noting that World War II president Franklin Roosevelt and Cold War president John F Kennedy were Democrats.

"Don't tell me that Democrats won't defend this country," Obama said. "The Bush-McCain foreign policy has squandered the legacy that generations of Americans - Democrats and Republicans - have built, and we are to restore that legacy."

He would also "restore our moral standing so that America is once more the last, best hope for all who are called to the cause of freedom".