John Lichfield: The battle lines are drawn

France will have a Sarko-versus-Ségo second round in May, to the delight of the gossip magazines

Nature abhors a vacuum. Politics, and especially French politics, detests an early leader in the opinion polls. What price two early leaders?

There are nearly eight months to go before the first round of the French presidential election. If one believes the polls, the outcome is already predictable. The representatives of France's two mainstream political "families" - centre-right and centre-left - will be Nicolas Sarkozy and Ségolène Royal. They will comfortably top the first-round poll in April, pushing the ugly extremes of right and left back into the shadows.

France will have a Sarko-versus-Ségo second round in May, to the delight of the gossip magazines and the fury of many established political figures.

After the triumphantly choreographed summer university of his party at the weekend, the interior minister, M. Sarkozy, 51, is all but enthroned as the Next Big Thing on the centre-right of French politics. He will be the man who will succeed to the mantle of Charles de Gaulle. Georges Pompidou, Valéry Giscard d'Estaing and Jacques Chirac.

The ebbing forces of "Chiraquie" are desperately (and disgracefully) praying for a serious world crisis to blow the upstart and internationally untested Sarko out of the water. Outright war in the Middle East might yet restore, they hope, the fortunes of the 73-year-old Chirac, or more likely, one of his creatures, the prime minister, Dominique de Villepin, or the defence minister, Michèle Alliot-Marie.

On the left, things are not quite so cut and dried. The re-emergence of the defeated and retired former prime minister Lionel Jospin, 69 - like a pterodactyl flying over the Eiffel Tower - has forced a re-evaluation of seeming certainties. The opinion polls still make Mme Royal, 52, the overwhelming favourite to be chosen by Socialist party members in November to become the first woman to lead a large French party into a presidential election.

Both "Sarko" and "Ségo" have run clever pre-campaign campaigns. Both have also enjoyed something essential to generals and politicians: luck. One by one, Sarkozy's rivals have auto-destructed. M. Chirac was knocked out of the reckoning by his poor health, the rejection of the EU constitution by French voters and his slow, vague reaction to the suburban riots in November and the student unrest last spring. M. de Villepin wrecked his own hopes with his alleged, tangential involvement in an attempt to "smear" Sarkozy and an abortive youth employment law.

The interior minister has been presented with a clear battlefield on the centre-right. He has been able to move from a kind of loud-mouthed, authoritarian liberalism to a softer, more reassuring (but vaguer) version of "Sarkozyisme": talking of a "new French model" and a "new humanism". The near break-up of his marriage last year has also turned to his advantage. Cécilia Sarkozy has been persuaded, or bullied, into returning - a heart-warming love story that has been carefully leaked to the "people" magazines.

Meanwhile. Ségolène Royal has run a brilliant campaign of creative vacuity which may well serve as a model of post-modern politics well beyond France. By clever use of the internet, she has persuaded scores of thousands of people that they are part of her campaign.

Far from hurting her (so far), her gender has become part of her appeal. The fact that she is a woman, and talks about so-called "woman's issues" like the family, education, the environment, has chimed with the anti-political but skittish mood of France. The French, both men and women. know that they want a different kind of politician. Ségo seems ideal: different but unthreatening.

Both Sarko and Ségo are old campaigners who have managed to persuade the electorate that they are new faces. Both are people who claim to have a direct line to "the people" but have a rather manipulative, demagogic relationship with the press. Both are tough but volatile, even fragile. Both are maddeningly vague on detail. Ségo is worse than Sarko in this respect. She talks about admiring the Scandinavian model and some aspects of Blairism, but says little about how they can be imported to France.

But even Sarkozy's best-selling book on his political roots and programme is more about style than substance. It is evident that Sarkozy would be a hands-on president, but not so clear what he would actually do with his hands. He talks of abolishing the 35-hour week, reducing taxes, restoring faith in work and cutting unemployment. But how will he avoid the trap set for all French leaders in recent years? The people say they want change, but then pour on to the streets to block all changes.

To avoid outright conflict, and a new lurch to the political extremes, the post-2007 president must be someone capable of preserving the best of France, while releasing and channelling the suppressed energy of the French: the third generation immigrants, the overqualified and underemployed young, the would-be entrepreneurs stifled by taxes and bureaucracy.

Which of Ségo or Sarko is likely to be the persuasive, brave leader which France needs - and partly fears? Maybe neither. Of the two, if you believe his self-image, Sarkozy is likely to be the more courageous and the more active. He is also likely to be the more volatile and the more dangerous.