Can Chirac keep his dreams afloat amid claims of graft, kickbacks and holiday bills of £240,000?

The cruel, unspoken joy of watching a great escapologist at work is the possibility that, one day, he may fail to escape.

Will Harry Houdini, chained inside a metal coffin, drown in New York harbour? Will President Jacques Chirac, one of the great political survivors and escapologists of modern times, fail to leap clear of the latest in a long chain of allegations of corruption? This, in one form or another, will be the question in the minds of French people when President Chirac appears, full of his usual bonhomie and blokishness, in their living rooms on Saturday to give his traditional television interview for Bastille Day.

Mr Chirac's daughter, Claude, was questioned by magistrates yesterday as a noose of criminal investigations into alleged bribes and the source of the cash used to pay for £240,000 in holidays tightened around the President, his family and friends. The newest allegations are more explosive than anything that has gone before, and for once do not concern illegal campaign funding, a subject that bores the French electorate. They imply that the President, while Mayor of Paris, took public cash, or kick-backs on public contracts, to pay for his and his family's personal pleasures.

Between 1992 and 1995, before he was President, Mr Chirac spent £240,000 in cash on holidays for himself, his family and his friends. Three investigating magistrates want to know the source of the fat wads of Fr500 (£50) notes sent, personally, by Mayor Chirac in manilla envelopes to his favourite travel agent in the Paris suburbs.

The magistrates suspect the cash came from the £60m in kick-backs paid – also in Fr500 notes – by construction companies who wished to secure a slice of a programme for modernising schools in the greater Paris area.

It has been established that the money was handed over to officials of Mr Chirac's centre-right RPR party, and shared with political allies, and opponents, supposedly to fund election campaigns. Did the future President also take some of the (originally taxpayers') cash to pay for the vacances de Monsieur Chirac? Legally, the President appeared to be in the clear, until this week, thanks to the immunity from prosecution bestowed (according to one interpretation of the French constitution) on the office of head of state.

Politically, Mr Chirac is chained and locked in a trunk, with the time ticking away to the presidential elections next April. He must, on television on Saturday, offer some more plausible explanation of the source of the Fr500 notes, with which he paid for 20 holidays for himself, and a large entourage, in Mauritius, New York (by Concorde), Japan, Austria, the Alps and the Breton coast. Why did he pay in cash? Where did the cash come from? Mr Chirac's friends were saying yesterday that he had a "full explanation" that would cause the whole scandal to "deflate overnight".

The explanations had better be more convincing than those originally offered, which were either implausible or absurd. A hasty riposte was drafted by the President when the story first leaked on a news magazine website three Sundays ago. The presidential residence, the Elysée Palace, said the money came from Chirac family resources but also from the cash "bonuses" that Mr Chirac had received from "secret" state slush funds when he was Prime Minister (in the 1980s) and a minister (in the 1960s and 1970s). But there is no record in the Chirac family tax returns – as legally there should have been – of such large sums being taken in cash from officially declared, "private" family assets.

The cash bonuses paid to ministers and senior officials are a long, bizarre, French tradition. By referring to these cash payments from "secret funds" (which are actually not in the slightest bit secret), Mr Chirac started a political hare running – as no doubt he had intended. The funds are also covered by "defence secrecy", which is useful in keeping magistrates at bay.

To thicken the smoke-screen, various Chirac allies put on concerned and wounded expressions. Like the French police commissioner in Casablanca, they said how "shocked, truly shocked" they were to hear that "secret" state funds were being paid to ministers in cash. They included three former centre-right ministers who had accepted the legal but dubious cash bonuses while in office.

In truth, the ministerial bonuses, though a scandal in themselves, are a giant red herring; and one that may end up by biting Mr Chirac.

When Mr Chirac took the first of his cash-on-the-nail holidays, he had not been Prime Minister for four years. He had not been a cabinet minister for 18 years.

Is the French nation to believe that the Mayor of Paris and future President of the Republic stored up hundreds of thousands of francs of ministerial cash bonuses in his mattress, or his socks, for four years or even for two decades? Throughout the high inflation of the 1980s and early 1990s? The President stands accused as much by his own fraudulent line of defence as by the magistrates' line of inquiry.

One possible escape route for Mr Chirac, and one that has already been discussed in the Elysée Palace, is to play the martyr on Saturday; to claim that all these allegations and manouevres are politically motivated; that he is a "permanent victim" of bogus charges, as he claimed on the same occasion last year. The problem this time is that the magistrates have already begun to question members of his immediate family and political entourage.

Claude Chirac, his daughter and media adviser, told investigators yesterday she did not know where the money for the trips had come from.

The long-time head of his private office, Anne Lhéritier was summoned to see the magistrates on Tuesday. So were Marianne Legendre, his head secretary, and Senator Maurice Ulrich, a close political adviser, who went along on several of the paid-in-cash holidays. There is even talk that the magistrates are ready to summon the first lady, Bernadette Chirac, which would be unprecedented.

Can President Chirac hide behind his immunity and claim martyrdom while his family, friends and close officials go through the legal grinder? How would the public react to that? In the past two days, even Mr Chirac's constitutional and legal immunity has been called in to question. Two of France's most senior public prosecutors have disagreed openly on whether the President should answer questions from magistrates.

The Paris public prosecutor said he should. The procureur general of the Paris appeal court said he should not. It is now up to the trio of magistrates investigating the school kick-backs to decide whether to send Mr Chirac a witness summons. Another magistrate, investigating separate allegations of corruption in the Paris town hall, sent a witness summons to "Chirac, Jacques" earlier this year. The President haughtily refused to answer the magistrate's letter. Now, whether the other magistrates summon Mr Chirac or not, one of the two warring prosecutors is bound to appeal against the decision. The question of his immunity from criminal prosecution is therefore likely to go, for the first time, to the highest appeal court, the Cour de Cassation.

Nine months before the first round of the presidential elections, France is about to be plunged into an ugly legal and constitutional battle over whether its head of state can face criminal proceedings.

Mr Chirac has not survived for so long in French politics – he was first a minister under De Gaulle and Pompidou in 1967 – by accident. He is a fighter. He has a supernatural ability to alter his most deeply held convictions for electoral gain and to allow his friends to take the blame for the trail of doubtful financial practices in his wake.

It is partly the sheer nerve – culot in French – of Jacques Chirac that endears him to the French people. But even his friends have been jolted by the latest allegations. To pay out such large sums in cash – whatever its origins – when magistrates were already closing in on the corruption of other French political figures was an "act of insanity", they say.

This is another aspect of President Chirac's culot. He has a deep conviction – perhaps his only deep conviction – that he is untouchable. This time, he may be wrong. The amount the Chiracs and friends spent on 20 private holidays in four years – £240,000 – is equivalent to a lifetime's earnings for someone on the French minimum wage. If the French electorate becomes convinced, or even suspicious, that the holiday were paid for with kick-backs on public cash Mr Chirac could be fatally wounded politically, whatever happens to him legally.

Les Vacances de Monsieur Chirac – or perhaps Monsieur Culot – may yet force him into a permanent holiday.