Leading article: White House race could yet turn into a real cliff-hanger

For those watching the US primary elections for their political excitement – and there are surprisingly many around the world – Super Tuesday's results came as both something of a let-down and a source of cheer. The disappointment is in what they did not do. The succession of results throughout the night failed to give John McCain the certainty of the Republican nomination that many had predicted, although it put him pretty close to it. Nor did the Democrat results give either Hillary Clinton or Barack Obama the decisive lead their more optimistic supporters might have hoped for. The source of cheer comes from the fact that this race is far from over. There is plenty in the progress towards the Democratic convention to test the two main candidates, and enough competition left in the Republican ranks to keep Mr McCain from taking his course for granted.

In so far as politics has become a sporting event, that is to the good. All the surveys suggest that the public is most put off politics when the outcome seems most certain. Give voters a tight contest and they sense their power and their interest. In so far as politics is about the election of the most powerful leader in the western world, then the whole primary process may arouse more mixed feelings. The harder the struggle to gain the nomination, the more money comes into play. Supporters of Mr Obama and Mr McCain are in the odd positionof proclaiming their candidate as the voice from the outside, while notching up their success in funds raised.

Nor is a tough primary battle necessarily the best way of bringing out the policies of the would-be Presidents. As the going gets tenser and money plays a more important role, the campaigning and the advertising concentrates more on personality and image. Mr McCain is presented as a proven hero and a resolute fighter, and equally attacked for being irascible and grudge-driven. Mrs Clinton is variously presented as figure from the past and feminist pioneer for the future, Mr Obama as a breath of fresh air and an ingénue. Each is at pains to distance themselves from President Bush and his policies, a position Mr McCain has exploited particularly skilfully. But in their speeches it is difficult to determine exactly what that difference means in terms of economic policy, foreign interventions and domestic priorities.

And yet, for all that, the US primary race is proving remarkably effective in bringing out and giving expression to the differences within American politics and society. The country is almost the last democracy to keep to a two-party division. In the past, this has been broken, with usually only limited effect, by the entry of independent candidates. This time, despite the suggestions that Michael Bloomberg might enter the race, the politicking has been confined to the two parties. The primaries have thus become a means of teasing out variety in a way that the presidential contest no longer does. While Mr McCain has taken on the mantle of the Republican centre, Mike Huckabee has muscled in with the views of the religious right and Mitt Romney has come to speak for the business-oriented right. Where Mrs Clinton has picked up traditional Democrat voters among the Hispanics and the poor and added to it the women's vote, Mr Obama has seized the votes of the young and the blacks. He has traded on the desire for change, she on the need for experience and Mr McCain on the patriotic centre. Commentators may talk of a dream ticket of McCain-Huckabee and Clinton-Obama, but it is far too early for that. And quite properly so.

US politics are not being re-forged in this election. If anything, the style and structure of the politicking is quite traditional. But it is being opened up in a way that even the most cynical observers of American democracy must concede is free and open.

For rolling comment on the US election visit: independent.co.uk/campaign08