Editorial: Edwards is tinder for a dry Kerry

American vice-presidential candidates have generally had little influence on the outcome of elections. Indeed, even among the successful, only those who eventually graduate to the White House or commit Dan Quayle-like blunders endure in the memory. Democrats, however, believe this year will be different. John Edwards, the North Carolina senator selected by John Kerry as his running mate, is seen as the decisive point of difference in what seems certain to be a close presidential contest.

It is easy to see why the Democrats are enthused. Mr Edwards was the choice of most to inject youthful energy, charisma and Southern populism into the party's campaign. Yet, in part, that very enthusiasm speaks volumes about their presidential candidate's shortcomings. Mr Kerry is widely seen as wooden and belonging to the Northern liberal elite. Thus, Mr Edwards' selection is all about balance and style rather than the political experience which the current Vice-President, Dick Cheney, brought to George W. Bush's successful campaign.

To Mr Edwards will fall the task of re-energising the Democrat campaign. Mr Kerry's profile has barely lifted since he won the right to challenge Mr Bush. To a degree, this might have been a calculated policy. The President's approval ratings have been slipping in the morass of Iraq. Mr Kerry has been able to observe this from the sidelines. Indeed, to have attacked Mr Bush over his failed policies in Iraq would have risked being seen as unpatriotic.

Nonetheless, Mr Kerry cannot maintain a posture of near invisibility and hope the American people decide that Iraq disqualifies Mr Bush from a second term. The latest opinion polls show the two men neck and neck, although, significantly, Mr Kerry has a strong lead among self-identified independent voters. Mr Edwards will play an important role if that element of support is to be cemented in, especially in the largely Mid-Western "battleground" states.

Democrats hope his appeal, based on strong campaigning skills and a flair often likened to Bill Clinton, will play well with younger voters, women and the working and middle classes. His constant message is that there are now two Americas - one for the wealthy and one for those struggling to get by. For the Democrats to win on November 2, that message will have to strike a chord in the likes of Ohio, the bellwether state where polls show voter support for Mr Kerry on the economy but backing for Mr Bush on "cultural" issues.

The Democrats cannot, however, take it for granted that the economy will be a point of weakness for the President. It is widely expected to grow by 4.6 per cent or better this year, the fastest in two decades. A total of 1.5 million new jobs have been created since last August. It is now by no means certain that Mr Bush will become only the second President since Herbert Hoover in the Great Depression to lose jobs - that is, oversee a rise in unemployment - while in office - the other was Mr Bush's father, George Bush senior.

The White House will highlight the revival at every opportunity. In response, the Democrats will point to the woes of the Bush Administration's first three years and the fact that many laid-off workers have been forced to take lower-paying jobs.

The high tide for the challengers will, in all probability, fall between now and the immediate aftermath of the Democrat convention in Boston this month. The announcement of an exciting and energetic vice-presidential candidate and the pizazz associated with formal anointing should prompt a surge in support for the Kerry-Edwards ticket.

Mr Bush, however, has a bigger war chest and an improving economy on which to draw. He can also take comfort from the fact that American elections are usually decided on domestic issues, unless the country has an overseas catastrophe on its hands. Iraq, of course, could yet be that calamity. But Mr Bush can also look forward to probing the inexperience of the Democrats' vice-presidential candidate. The youthfulness that is among Mr Edwards' strengths could also be his undoing.