DENVER - AFTER two nights of high drama and emotion here, Joseph Biden has several tough acts to follow Wednesday as he steps up to claim the Democratic nomination for US vice president.

With many both inside and outside his party still believing that the post should have gone to Mrs Hillary Clinton, Mr Biden, who has sat in the US Senate for 36 years, will have to pull out all the stops at the convention here.

He is now part of a historic ticket, running with Mr Barack Obama the first African-American ever elected by a major US political party as its presidential candidate.

Mr Obama has presented Mr Biden, 65, as the perfect attack dog to maul Republican rival John McCain on US voters' top concern: the economy.

'I think he can help shape a long term strategy to keep America more secure after the disastrous economic and foreign policies that characterised the last eight years,' Mr Obama said earlier this week.

But his call to the veteran Delaware senator has been seen by many as an admission that Mr Obama's own meteoric rise and crusade for change are undercut by inexperience and fragile bonds with blue-collar Democrats.

The choice cemented the Democratic presidential ticket in the early hours of Saturday, and balances Mr Obama's thin resume on the national stage with a man who has spent more than half his life in the Senate.

Mr Biden's wit and sharp rhetorical skills were to be put to the test on Wednesday, as he prepared to step up to the podium just after a highly-anticipated address by former president Bill Clinton.

Clinton addresses convention
After a rapturous welcome from the crowd, Mr Clinton on Wednesday said for the first time that he believed Democratic nominee Barack Obama was 'ready' to be president and he would work to elect.

'Barack Obama is ready to lead America and restore American leadership in the world,' Mr Clinton told the convention.

He was speaking a day after his wife, Hillary, wowed the convention center with a high-octane, foot-stomping speech calling for the party to unite behind Mr Obama, who defeated her in the party's primaries.

The son of a used-car salesman, Mr Biden is proud of his working-class roots, is a garrulous, Irish Catholic with an earthy sense of humour, who often invokes 'My dear old Mom, God love her,' during intense foreign policy debates.

He relishes political combat, a boon to an Obama campaign sometimes seen as lacking fire in the belly.

Mr Obama's chief lieutenants and supporters have also denied that Mr Biden compromised the Illinois senator's mantra of change.

'He's got the passion to lift up middle-class Americans. He hasn't forgotten his working class roots,' Mr Obama said this week, adding Mr Biden has 'the expertise that will make him a great counselor on international crises.'

Mr Biden's style is in a sharp contrast with his younger colleague, and he is not a natural number two - so he will have to learn to be a subordinate.

Voters will get a first chance to see the Democratic ticket at work this week, when the new running mates head out on their first joint campaign swing after the week's convention in a bus tour of battleground states.

The candidates and their wives, Michelle Obama and Jill Biden, will leave Denver Friday for Pennsylvania, first stop of their 'On the Road to Change' bus tour, Obama aides said in statement on Wednesday.

The tour by the White House hopefuls will then move on to Ohio and Michigan, two other rust-belt states that could prove pivotal to success in November's presidential elections.

On Tuesday, the Delaware senator shed a tear as he thanked his state supporters for standing by him through his tragedy-scarred lifetime.

'This is a great honour, this is a great honor to be nominated vice president of the United States,' said Mr Biden, who lost his first wife and infant daughter in a car crash just after being elected to the Senate in 1972.

'I am proud of it, I don't mean in any way to diminish it. But it pales in comparison to the honour I have had representing you.' -- AFP