Confirmed as the Democratic Party’s nominee for President of the United States yesterday, Barack Obama is expected to give the speech of his life later today when he begins his final push for the White House.

Americans will vote on November 4th, and with neither Obama nor his presumptive Republican opponent John McCain surging ahead in the polls his performance, which will be broadcast live in the UK at 3am BST, will be crucial.

Four years ago Obama came to national attention with a speech to the Democratic convention.

His soaring oratory on that occasion will have to be at least matched tonight if he is seize the headlines and the momentum from McCain.

His nomination was suitably dramatic.

Delegates from the states started the roll call in alphabetical order, but it was interrupted by Hillary Clinton and the New York delegation.

“In the spirit of unity, let’s declare together, in one voice, that Barack Obama is our candidate and he will be our President,” she said, and by acclamation the process was ended and Obama was declared the nominee.

Yesterday the last Democrat to hold the Presidency, Bill Clinton, also gave a rousing endorsement of the young political star who defeated his wife in a hard-fought nomination process.

“The primary began with an all-star line up and came down to two remarkable Americans locked in a hard fought contest to the very end,” he said.

“The campaign generated so much heat it increased global warming.

“In the end, my candidate didn’t win.

“But I’m very proud of the campaign she ran: she never quit on the people she stood up for, on the changes she pushed for, on the future she wants for all our children.

“Hillary told us in no uncertain terms that she’ll do everything she can to elect Barack Obama.

“That makes two of us.

“Actually that makes 18 million of us – because, like Hillary, I want all of you who supported her to vote for Barack Obama in November.”

President Clinton, who took office in 1993 at the age of 46, also dismissed arguments that Obama, at 47, is not ready to lead.

“The Republicans said I was too young and too inexperienced to be Commander-in-Chief. Sound familiar?

“It didn’t work in 1992, because we were on the right side of history. And it won’t work in 2008, because Barack Obama is on the right side of history.

“The values of freedom and equal opportunity which have given him his historic chance will drive him as President to give all Americans, regardless of race, religion, gender, sexual orientation or disability, their chance to build a decent life, and to show our humanity, as well as our strength, to the world.”

President Clinton said that the 44th President will have to “rebuild the American Dream and restore America’s standing in the world.

“Everything I learned in my eight years as President and in the work I’ve done since, in America and across the globe, has convinced me that Barack Obama is the man for this job.

“He has a remarkable ability to inspire people, to raise our hopes and rally us to high purpose. He has the intelligence and curiosity every successful President needs.

“His policies on the economy, taxes, health care and energy are far superior to the Republican alternatives.

“He has shown a clear grasp of our foreign policy and national security challenges, and a firm commitment to repair our badly strained military.

“His family heritage and life experiences have given him a unique capacity to lead our increasingly diverse nation and to restore our leadership in an ever more interdependent world. The long, hard primary tested and strengthened him.

“And in his first Presidential decision, the selection of a running mate, he hit it out of the park.”

Earlier yesterday Senator Joe Biden was nominated and accepted the Vice Presidential candidate.

“John McCain is my friend,” he said. “But I profoundly disagree with the direction that John wants to take the country.

“For example, John thinks that during the Bush years, ‘We’ve made great economic progress.’ I think it’s been abysmal.”

Mr Obama made a surprise appearance at Senator Biden’s side last night. His speech tonight, in front a crowd of 75,000 at a football stadium, will be held on the anniversary of Martin Luther King’s 1963 “I Have A Dream” speech.

“Senator Obama’s speech tonight will be as he himself has characterised it, more workmanlike, a very direct conversation with the American people about the choice we face in this election,” campaign spokeswoman Anita Dunn said at a press briefing.

“About the risk of staying on the same path we’re on, the risk of just more of the same versus the change we need.”

The Republicans will gather in St Paul, Minnesota, next week. Senator McCain has not yet announced who will be his running mate.

Two former state Governors, Tom Ridge of Pennsylvania and former Presidential candidate, Mitt Romney of Massachusetts, are the front runners.