Enter the assassin

The first, fateful meeting between Jacques and Nicolas was in the wings of a Gaullist party conference in Nice in June 1975. Jacques Chirac was 43 years old and (already) Prime Minister. He was manoeuvring to take over the old Gaullist party and planning to stab in the back his nominal boss, the anti-Gaullist President of the Republic, Valéry Giscard d'Estaing. Nicolas Sarkozy was 20, a law student with Transylvanian good looks, the estranged son of an exiled Hungarian minor aristocrat. He had been shipped to Nice from Paris as part of a rent-a-mob of young Chirac supporters, whose job was to make the unpopular, youthful Prime Minister look like the man of the future, the choice of the conservative, non-revolutionary young.

Jacques' first words to Nicolas were: "Are you Sarkozy? You've got two minutes."

The young man went out on stage and spoke, triumphantly, for 20 minutes. Twenty-nine years later, Nicolas Sarkozy is still talking. Endlessly.

Now, however, the roles have changed. Sarkozy is a boyish 48, a popular and frenetic Minister of the Interior. He has declared himself to be the man of France's future; the impatient would-be successor to his ageing boss; the young and dynamic man who can save France from the threats of the extreme right, and extreme left, from internal division and economic decline.

The ageing boss is, of course, Jacques Chirac, 71, President of the Republic (still) and unwilling to be put in a political old people's home. All power struggles are fascinating. This one is elemental. Oedipal, even.

Sarkozy - or "Sarko", as he is called by the French press - was once Chirac's adopted political son. In the late 1980s, he had a love affair with Chirac's younger daughter, Claude. Despite his relative youth, he was present at the birth in 1976 of Chirac's neo-Gaullist party, the RPR (Rassemblement Pour la République, now defunct). Sarkozy is still one of the few politicians whom Chirac addresses as "tu" rather than the formal "vous".

With his energy, his cheek, his uncloaked ambition, his self-confidence, his tactical brilliance, his occasional tactical stupidity, Sarkozy resembles the young Chirac. There are also important differences. Chirac is tall, Sarkozy is short. Sarkozy is a more modern and more complex politician than Chirac, a centre-right Gallic version of Tony Blair - a man obsessed with image who sometimes takes surprising risks to defend unpopular positions.

For two months now, the virtual son, or virtual son-in-law, has been in semi-declared revolt against the father. Asked by a television interviewer in November whether he ever imagined himself as president while he was shaving, Sarkozy replied: "Yes, and not only when I'm shaving."

There are still three years to go before France's next presidential election. Despite economic problems, Chirac remains broadly popular, partly thanks to his rearguard action against the war on Iraq. Chirac has let it be known that he is considering running for a third term in 2007. Sarkozy has let it be known that, after 35 years of prominence but little achievement, Jacques Chirac is a man of the past. "In politics, you have to know when it is time to give up your place," he told television- viewers recently.

Squeezed in the middle is the cuddly but over-promoted Prime Minister, Jean-Pierre Raffarin, a man plucked from relative obscurity by Chirac in 2002, partly as a deliberate snub to Sarkozy. In his 20 months in office, struggling to impose modest reforms in economic hard times, Raffarin's popularity has plummeted (although it is now recovering). In the same period, Sarkozy, the No 2 in Raffarin's government, has soared to the top of the political popularity charts.

Until two years ago, Sarkozy was regarded in la France profonde as a pointy-headed intellectual from the Parisian élite. The foreign name and looks did not help. As France's "premier flic" (top cop), he has reinvented himself, with the determined help of his second wife, Cécilia, a half-Spanish, very American prototype for a new generation of French power wives.

Sarkozy is a teetotaller who binges on chocolate and sweets and runs 6km on the Champ-de-Mars most mornings. He has thrown himself with whirlwind energy into "solving" the problems of crime and insecurity, which President Chirac had persuaded the French people were their primary concern during the presidential and parliamentary elections in 2002. (In truth, crime in France is well behind the levels in Britain, never mind the US.)

Sarkozy has pushed through new laws to increase police powers, to modernise the police and gendarmerie, and to sweep begging and prostitution (nominally) from the streets. He has popped up, in casual coat and open shirt, in the early hours in almost every police HQ in France. He has closed the Sangatte refugee camp and persuaded Britain to take 70 per cent of the inmates (a good deal for everyone in France, except the new refugees still turning up on the streets of Calais). He will present figures today showing a sharp reduction in petty and violent crime.

He has made two impressive, hour-long television appearances, fielding questions from political opponents in simple, direct language. In one of them, he publicly routed and humiliated the veteran leader of the racist Front National, Jean-Marie Le Pen (something that no one has ever achieved before).

Sarkozy is a new kind of French politician but how new is open to question. He is arrogant but not pompous; he is driven, he insists, by results rather than ideology or egotism. He encourages his officials to call him "tu" or Nicolas, rather than "Monsieur le Ministre".

He has not been to the usual finishing- schools of the French political and administrative élite. In 1983, at the age of 28, he was elected the youngest mayor in France, in one of the richest communes in France, Neuilly-sur-Seine, a ghetto for the wealthy and powerful between Paris proper and the skyscrapers of La Défense. Like Tony Blair, he defies political categories. He does not buy, in bulk, the standard prejudices of the French right. He is authoritarian and ready to crack down on illegal immigration, but has campaigned for "positive discrimination" in favour of second-generation Arab and black French men and women. He opposed, initially, the law banning Muslim headscarves from state schools.

He believes in public investment and an important role for the state, but would like to see a more economically liberal and dynamic France. He - no more than anyone else - has yet to explain how you square that circle without breaking the entrenched privileges of France's legions of public-sector employees. He is unapologetic about his belief in the European Union. He has friendships, and is admired, across the right-left divide. He is also detested across the right-left divide.

Nicolas Sarkozy de Nagy-Bocsa was born in Paris on 28 January 1955. His father Pal was a Hungarian aristocratic charmer and refugee from Communism. His mother, Andrée is a formidable half-Jewish lawyer, who supported and raised Sarkozy and his two brothers after their father drifted away to the United States. Sarkozy - to the amusement of his mother and brothers - used to exaggerate the poverty of his background, claiming to have come from "nothing", and even to be an immigrant "child of the inner suburbs" (like claiming to be a ghetto-child in the US).

By the mid-1980s, when Chirac was mayor of Paris and plotting the second of his four presidential campaigns (two defeats, two victories), the young mayor of Neuilly became one of the Gaullist leader's closest confidants. He became, in fact, a confidant to the entire Chirac clan.

Although he was married, he became romantically entangled with Chirac's daughter Claude. Chirac's wife Bernadette is said to have regarded him as the perfect possible son-in-law. The relationship ended amicably enough. Sarkozy was a witness at Claude's wedding to a journalist in 1992. At about the time that the relationship with Claude Chirac ended, Sarkozy met the woman who was to become his second wife. The second Madame Sarkozy was then - implausibly - married to an ageing, gushing French TV presenter called Jacques Martin, a sort of French Hughie Green. She became friends with Sarkozy's first wife Marie, before falling for Sarkozy. There was a double divorce, but not before M. Martin walked into the Neuilly town hall and punched M. Sarkozy on the nose in public.

The friendship with the Chiracs collapsed circa 1993-4, when Sarkozy - then budget minister - let it be known that he was going to support Edouard Balladur, the prime minister and former Chirac acolyte, in the 1995 presidential election. Jacques Chirac felt politically betrayed. Worse, Chirac's wife and daughter felt personally humiliated by someone who had been allowed to cross the threshold of family intimacy, a frontier that is jealously guarded in la France haute-bourgeoise. Bernadette Chirac is said to have remarked: "And to think, he has seen us in our nightclothes..."

Sarkozy's former relationship with Claude - now President Chirac's communications adviser - is hinted at, but rarely openly discussed, in the French media because of the French law protecting personal privacy. It is, however, an active ingredient in the poisonous chemistry of the present quarrel. Sarkozy backed the wrong horse in 1995. Chirac saw off Balladur and became president. Since then, Sarkozy has worked hard to re-establish himself as an important figure in French politics - without Chirac's support or patronage.

He has built, Chirac-like, his own network of friends and admirers, ranging from the rich, such as Bernard Arnault, the LVMH tycoon, to the celebrated, such as the actor Christian "Astérix" Clavier, to grass-roots political operatives all over France. His success is a tribute to his ability; and to the generally mediocre calibre of most other politicians on the French right.

Like the sumo wrestlers that Chirac adores, the two men are now circling each other, waiting for mistakes or openings. "Sarko" has become too popular for Chirac to fire. He would be more dangerous outside the government than inside. Le Monde quoted him as having said privately: "Chirac doesn't hate me. It's worse than that. He's scared of me."

On the other hand, Sarkozy has to be careful. Chirac is a survivor and a ruthless political operative, a master of the put-down. He is looking for ways to trip and denigrate a young (or youngish) man who has, possibly, revealed his hand too soon. Sarkozy went to China last week to sign an immigration agreement. He was received by the President, Hu Jintao - quite a tribute. Chirac was publicly un-amazed. "I, too, was received by the Chinese president when I was nothing," he told journalists.

But even Chirac cannot last forever. The left is scattered. The other centre-right candidates are dull or limited. Who can stop Sarkozy from being president one day - maybe even the next time around?

The philosopher and political commentator Marcel Gauchet pays tribute to Sarkozy's energy and rather American talent for image-building, but says that a French politician, to capture the ultimate prize, must represent a tradition, or a set of values, a "certain idea of France. Sarkozy represents nothing but himself...". A former socialist minister, speaking off the record, describes Sarkozy as, "a real shark... he has to keep moving all the time or he'll die". Another leading left-wing politician - who has friendly relations with Sarkozy - says that both right and left are mesmerised by the hyperactive interior minister, but convinced that he will crash to earth sooner rather than later. "They tend to see his cunning rather than his courage," he said. "It was clever of Sarkozy to take on Chirac so directly... it lifted him up a whole division from one of a number of contenders for the presidential crown, to the contender. That took cunning, but it also took the kind of courage that no one much else has, either on the right or the left."

Bernadette Chirac - one of the shrewdest political judges in France - says that, all rancour apart, Sarkozy does not have the stuff of French presidents. She tells friends that he is too short; that he has no base in rural France; that he is too young and too obviously eager; that he looks too foreign. She may be right. Sarkozy might make an excellent prime minister in a parliamentary system of government. To be accepted by the French as the executive head of state - the nation's uncle-confessor - demands a further, mysterious, spiritual-theatrical dimension.

Or, at least, it has until now. Sarkozy believes that, next time around, France will wants someone younger, more direct, who wants to do something, rather than just represent something. But do what?

"I have made all the others look old-fashioned," he is reported to have said, modestly, after one of his TV appearances. "I have shown that people are not really bored with politics. They are bored with people who have nothing to say."

And yet, what Nicolas Sarkozy has to "say", and what he would "do" as president, remain curiously vague. He knows that the sterile electioneering and careerism that has dominated the Mitterrand-Chirac era can no longer win votes in our disaffected, anti-political age. Careerism is no longer enough, even for careerists. If the menacing extremes of the left and the right are to be kept at bay, the next generation of French leaders must offer action and results. It remains to be seen whether "Sarko" is the man of action that France craves, or merely - like his old mentor, Chirac - an Action Man-impersonator.