Outside Joe Biden's modest Delaware home yesterday morning was a stack of four empty boxes from the local Grotto Pizza company. Inside, the Democratic vice-presidential nominee and a team of twitchy advisers were completing three full days of rehearsals for tonight's televised debate with Sarah Palin.

Despite having spent 34 more years than his opponent on the national stage - or, maybe, because of that experience - he is certainly not taking this clash lightly.

Sparring sessions have been organised with Jennifer Granholm, Michigan's Governor, playing the role of Mrs Palin. Mr Obama's strategists David Axelrod and Anita Dunn, have been in Wilmington this week coaching him. “I think Governor Palin is a skilled politician," said Mr Axelrod, "and we're going to treat her with the respect that she deserves."

They know that Mr Biden can come across as condescending, especially to someone like Mrs Palin who clearly does not have the knowledge that comes with six terms in the Senate and the chairmanship of the Foreign Relations Committee.

So, in recent weeks, the 65-year-old Senator has been given advice from Democratic colleagues including Hillary Clinton, Barbara Boxer and Dianne Feinstein about how to debate with the first female Republican vice-presidential nominee without being over-bearing.

Loquacious, passionate and well-informed, Mr Biden is widely regarded as being a sensible, heavyweight choice to be Barack Obama's running mate. But he has also all too often demonstrated a propensity, perhaps rooted in a childhood stammer, to trip over his eloquence and land in a steaming pile of words with foot firmly stuck in mouth.

His first White House run ended 20 years ago when he was caught plagiarising Neil Kinnock and, allegedly, exaggerating academic achievements. His second was almost still-born after describing Mr Obama as "the first mainstream African-American who is articulate and bright and clean".

In recent weeks, his gaffes have been coming so thick and fast that the Republicans have set up a dedicated website to monitor them. Last week he mangled history as he described how President Franklin Roosevelt got on television to deal with the Wall St crash. Herbert Hoover was president at the time and TV was not broadcast into American homes for another decade.

Along the way he managed to contradict Mr Obama's campaign on three occasions within a week. He declared that an advert attacking John McCain as old and out-of-touch was "terrible". Then video footage surfaced of him opposing clean coal power plant technology, a potentially damaging position in battleground states such as Ohio and Pennsylvania. Finally, Mr Obama even had to tick him off in public saying: "I think Joe should have waited" before criticising the bailout of AIG.

Republicans justifiably point out that if Mrs Palin had made such mistakes, the media would have had a field day. Instead, Mr Biden has largely been obscured in this presidential race, first by the focus on his rival and later by the financial tumult.

But this has also meant that most voters will not have his compelling story which, if told properly, could yet help bridge the gap between those working class Americans still suspicious of Mr Obama's exotic multi-ethnic and multi-national past.

Elected to the Senate in 1972 as a brash 29-year-old, his life was turned upside down a few weeks later by the death of his wife and baby daughter in a car crash as they picked up the family Christmas tree. The accident left his two sons seriously injured and Mr Biden has ever since commuted between Wilmington and Washington so he could be back at home each night.

This daily journey is a symbol of his accessability and an "Everyman" style by which he knows the names of every Amtrack conductor on the line. At Wilmington railway station, Bobby Jones, 63, described how Mr Biden sometimes stops by for a shoe shine. "He is at ease here and, unlike some people, he's always friendly. He once tried to help my son get into military school by writing a letter. It didn't work, but I like him."

Mr Biden may have a big mouth but he has a heart to match, say his admirers. He has been seen to weep during campaign stops when talking about his family while also showing a fire that Mr Obama lacks as he rails against the iniquities suffered by voters on health, education and jobs.

James Baker, the mayor of Wilmington, said: “We forgive him every once in a while when he says something dumb — ‘Oh, that’s just Joe.’ ”

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