Barack Obama kicked off his general election campaign yesterday by heading into the heart of Appalachia on a quest to win over the white working-class voters who backed Hillary Clinton overwhelmingly during their epic nomination battle.

Mr Obama, in his first campaign rally since he clinched the nomination on Tuesday, held a town hall meeting in rural southern Virginia, seeking to prove that he can woo Mrs Clinton's supporters without the former First Lady at his side - or on his presidential ticket.

As Mr Obama's aides began indicating that Mrs Clinton's chances of becoming his running-mate are slim, the Illinois Senator campaigned in Virginia instead with a trio of local politicians all considered possible vice-presidential candidates.

The trip to Virginia also served notice to the Republican nominee-elect John McCain that Mr Obama sees the state - which has not been won by a Democratic presidential candidate since 1964 - as a newly competitive battleground that could switch this year.

Virginia has been taking on a more Democratic hue and recent polls show that its 13 electoral college votes are highly competitive. Mr McCain visits the state on Monday and has already set up a campaign office there.

One of Mr Obama's first challenges is to win over the nearly 18 million Democratic voters who backed the former First Lady. Many are white, blue-collar Appalachians in critical swing states such as Pennsylvania, Ohio - and Virginia - who remain deeply suspicious, and at times openly hostile, to Mr Obama's candidacy.

At a town hall meeting in Bristol, on the Tennessee border, Mr Obama began by praising Mrs Clinton, saying: “I know I'm a better candidate because I ran against her. She's tough.”

He was introduced by Virginia's former Democratic Governor Mark Warner, who is considered instrumental in the Democratic resurgence in the state. He left office in 2006 with high approval ratings, and briefly flirted with the idea of a presidential bid in 2007. He is now heavily favoured to win an open Republican US Senate seat this November, although is likely to be on Mr Obama's list of possible vicepresidential picks.

Later in the day Mr Obama was due to appear at a huge rally in northern Virginia, in the Washington suburbs, a rapidly growing area that will be key to his hopes in November.

With him there were due to be two other Virginians with strong running-mate potential: Tim Kaine, the current Democratic Governor, and Jim Webb, a decorated Vietnam War veteran and first-term US senator with family ties in Appalachia.

Mr Webb is a particularly intriguing prospect as a vice-presidential nominee. A blunt-spoken former Marine and Navy Secretary under Ronald Reagan, he was raised in southwestern Virginia and would undoubtedly be a significant asset for Mr Obama in his efforts to win over rural, lower-income voters, especially in Appalachia, where he has deep Scottish-Irish roots.

He was given his first rifle, aged 8, by his father. One of his staffers was arrested in March 2007 for carrying a loaded pistol belonging to Mr Webb into the US Senate building.

In his new book, A Time to Fight, Mr Webb describes himself as “the only person in the history of Virginia to be elected to statewide office with a union card, two Purple Hearts and three tattoos”. One Democrat made clear his desire to be Mr Obama's running-mate: Bill Richardson, the New Mexico Governor, who dropped out of the presidential race earlier this year. An Energy Secretary under Bill Clinton, he broke with the former First Lady in March to endorse her rival.

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