Rupert Cornwell: Edwards is the Democrats' best natural politician since Clinton

In ideological terms too, they dovetail. John Kerry is consistently ranked among the most liberal Senators. Edwards - like any Democrat elected in the South - is notably more conservative

If vice-Presidential choices are about symmetry and 'balancing the ticket', then John Kerry's selection yesterday of John Edwards as his running mate to face George W. Bush and Dick Cheney in November illustrates the rule perfectly.

If vice-Presidential choices are about symmetry and 'balancing the ticket', then John Kerry's selection yesterday of John Edwards as his running mate to face George W. Bush and Dick Cheney in November illustrates the rule perfectly.

Yes, they are both rich white males who belong to the exclusive club that is the United States Senate - the first two-senator combination since John F. Kennedy and Lyndon Johnson narrowly defeated Richard Nixon and Henry Cabot Lodge in 1960.

That aside however, the symmetry analogy works perfectly. Kerry is by appearance (if not quite by birth) the archetypal 'Boston Brahmin,' the patrician NorthEasterner from Massachusetts, and a Catholic like the legendary former President whose initials he shares. His wealth in truth may come from his wife Teresa Heinz Kerry and her $1bn grocery fortune, but he projects the image of family and old money.

Edwards however is a son of the old south, born in South Carolina before moving to North Carolina which he has represented in the Senate since 1998. A former highly successful trial lawyer, Edwards is a rich man in his own right - but never misses the chance to remind audiences his father was a millworker. John Edwards can present himself as champion of the disadvantaged and half-forgotten 'other America' in a way that John Kerry never can.

In ideological terms too, they dovetail. John Kerry, opponent of the death penalty and committed enviromentalist, is consistently ranked among the most liberal Senators. Edwards - like any Democrat elected in the South - is notably more conservative.

Most important however, they complement each other in style. Kerry, as anyone who has suffered through one of his speeches, can give gravitas a bad name. He is ponderous and stodgy. A Kerry joke, like a German joke, is no laughing matter. The man from Massachusetts has many admirable qualities - personal courage proved in battle in Vietnam, a fine mind and a voluminous and fluent command of the issues. Not even he however would claim to be a spell-binding stump speaker.

Edwards however is another matter. He looks far younger than his 51 years and oozes charm. He is a natural populist, a brilliant communicator with a flashing smile and very quick wit. He is the best natural politician the Democratic party has produced since Bill Clinton. Indeed, some party professionals say that on the campaign trail, Edwards is even better. There could be no higher praise.

Doubts do remain - not least about the personal chemistry between the two men. More important even than symmetry, is the requirement that the candidate and his running-mate get on. During the primary season, relations were cordial, but not close. If John Kerry had gone for a real soulmate, he would picked his good friend Dick Gephardt, the former House majority leader.

But Gephardt was too familiar a face, a worthy but dull old pol who had been around Washington even longer than Kerry, and who could never fire up the party base. Edwards not only does precisely that. His zest and his moderate views also give him appeal far outside his southern base - as anyone who watched Edwards mesmerise audiences in places like New Hampshire can attest.

His 'Two Americas' speech resonates as powerfully in Ohio and in other industrial states where tens of thousands of jobs have been lost and where the 2004 election will almost certainly be decided, as it does in his native North Carolina.

Once Kerry had clinched the nomination, Edwards was the overwhelming choice of Democrats, both activists and ordinary voters, to be his running mate. Had he looked elsewhere, the Massachusetts senator would have had a good deal of explaining to do to his own supporters.

Of course questions remain. Edwards' background as a trial lawyer - if journalists and politicians are excluded, about the most unpopular profession in the land - may count against him. So too may a lack of experience, especially in foreign affairs, for a man who is the proverbial heartbeat from the Oval Office.

Last but not least, does the vice-presidential choice make any difference? In November voters will be choosing between two Presidential candidates, not their deputies. Very rarely in recent times have running mates had a crucial bearing on an election.

In 1960, Lyndon Johnson almost certainly tipped his home state of Texas to John F. Kennedy. Almost certainly, the elder George Bush would have had a better chance of winning a second term with a stronger vice-President than Dan Quayle. Edwards, beyond doubt, will help Kerry as Quayle never could help George H.W. Bush, But can he help peel off the odd state in the South, which Bush/Cheney swept in 2000? Polls suggested that Edwards might have lost his North Carolina Senate seat had he defended it this autumn.