New Hampshire Hillary Clinton's lead in the race for the White House is now so formidable that, even with his Nobel Peace Prize, Al Gore considers her unbeatable, according to his former campaign aides.

The former vice-president, whose supporters have formed a shadow campaign team in case he decides to run, has told friends he is reluctant to take on her formidable political organisation by throwing his hat into the ring.

One strong backer of Gore told The Sunday Telegraph that the Nobel Prize win had "increased his artillery" should he decide to risk making a second bid for White House, but said that this was now likely only if Hillary made an unexpected slip.

For the former first lady, Gore's reluctance to parlay his Nobel victory into his own attempt to reach the White House is further evidence of her remarkable political renaissance.

Currently Hillary is well ahead in the battle for the Democratic nomination and, unlike Gore, the front runner has been busy campaigning in crucial states such as New Hampshire.

To reporters watching her trying to reach out to voters in that key primary state, at one point she pauses in the mud to speak to a man in a wheelchair and a young family, Hillary appears a diminutive, school-marmish figure in her dark blue trouser suit.

But, almost seven years since her husband left the White House, Hillary has gone from cuckolded wife whose brief foray into healthcare policy was a humiliating disaster, to a two-term senator who claims to be the most experienced candidate in the race.

Polls show her leading her main Democratic rival, Barack Obama, by up to 33 points and seeing off each of the leading Republicans in a possible general election.