John Edwards stands before an all-white crowd in the small South Carolina town where he was born, his audience revved up by the banjo-playing bluegrass band and still guffawing at the introduction from Ben “Cooter” Jones, a former star of The Dukes of Hazzard television series.

Referring to this red-earthed region where many of his extended family still live, Mr Edwards declares in his best Southern drawl: “We ought to at least carry Oconee County if my relatives just turn out to vote!” After talking about his two glitzy opponents in today’s primary, Hillary Clinton and Barack Obama, Mr Edwards continues: “I’m the underdog. I know it. I understand it.”

Underdog is an understatement. Having campaigned for the presidency since the day he and John Kerry lost the election four years ago, the Democrats’ 2004 vice-presidential candidate has almost no chance of winning the nomination this year. He has lost Iowa, come third in New Hampshire, got his “butt kicked” in Nevada and is trailing both his rivals in his native South Carolina. Largely ignored by the press, and short of money, he also appears to be heading for a crushing nationwide defeat on February 5, “Super Tuesday”, when 22 states vote.

Yet Mr Edwards is vowing to press on. At first glance it looks like self-delusion, but his aides admit a cold calculation behind such obdurance. There is a role emerging for him, that of kingmaker, a position of power that could yet put him in the White House as the next vice-president.

As Mrs Clinton and Mr Obama slog it out, there is a growing possibility that the fight for the nomination could turn into a battle for delegates at the nominating convention this summer, with both arriving in Denver with less than the 50 per cent, or 2,025, needed. Already, it is mathematically impossible for either to win outright on Super Tuesday.

This puts Mr Edwards — who could end up with 15 per cent of the awarded delegates just by hanging on — in a position to determine the nomination in August. Brokered conventions are rare and were considered widely to be a thing of the past, but this year is already an extraordinary unpredictable presidential contest.

Tad Devine, a Democratic consultant, says that if Mr Edwards wins more than 15 per cent on February 5 he will be in an awfully influential position — one, some believe, that could allow him to demand the vice-presidential slot again. Mr Edwards’s potential strength lies in the way that the Democratic Party awards delegates after each state votes. To win the nomination a candidate needs 50 per cent plus one of a total of 4,048.

Each state, however, awards delegates under a system of proportional representation. The 22 states voting on February 5 award a third of their delegates to the winner of each state, and two-thirds to the winner of each congressional district within the state. In a close contest the delegates can be almost evenly awarded between the top two candidates — and the third-place finisher can do surprisingly well.

After Iowa — at face value a stunning, eight-point win for Mr Obama — he was awarded 16 delegates, Mrs Clinton 15 and Mr Edwards 14. Mrs Clinton’s New Hampshire victory five days later netted her nine delegates — the same as Mr Obama. Mr Edwards got four. Obama aides believe that Mrs Clinton is likely to win more states on “Super Tuesday” but that he could emerge with nearly as many of the 1,700 delegates available that day.

Mr Edwards’s chief strategist, Joe Trippi, believes that if he emerges with more than 200 delegates on February 5 — more than 10 per cent of the total — he has a chance to play kingmaker. If he does far better than expected, and wins 350, he will be in a position to influence the nomination.

Mr Edwards still insists that he is in the race to win but the main questions now are — if he can secure a kingmaking role — who would he support at the convention, and what he would ask in return? He appears more in tune with Mr Obama’s message of youth and change. Yet much of his core support is from blue-collar Democrats, who are far more likely to vote for Mrs Clinton.

If Mr Edwards loses badly in South Carolina, he could decide to quit. A clear front-runner could still emerge from Super Tuesday, with the nomination almost in the bag. If, though, he holds the key to the nomination in August, he would be in a good position to ask for the vice-presidential slot, or at least a senior Cabinet post. It’s the kind of deal that would have won the approval of Boss Hogg.

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