Although theoretically Mr Chirac is not involved in the campaign, the voters' stunning repudiation of the centre-right governing coalition in the first round of parliamentary elections last Sunday threatens him with five years of lame-duck presidency.
The President's subsequent firing, in effect, of his prime minister and long-time acolyte, Alain Juppe, puts him, more than ever, in the firing line. With no one else to blame a defeat in the second round on Sunday will be primarily a humiliation for Mr Chirac.
In a televised address to the nation last night, Mr Chirac appealed to French voters to spare France, the European Union - and himself - a long period of left-right power-sharing or "co-habitation".
The decision of the unpopular Mr Juppe to stand down, whatever the result this weekend, is supposed to bring out the tens of thousands of centre- right voters who stayed at home the first time around. The Elysee Palace said Mr Juppe's mid-election vanishing act - something unprecedented in French politics - would avoid "an excessive concentration on his personality" in the run-up to the decisive ballot.
It also creates a situation which must be unusual in any democracy. French voters are being asked to vote in a political vacuum. They are being asked to return a government without knowing who the leader of that government will be and without being given any detail on how its policies might change.
The rumours on Mr Chirac's likely choices for prime minister which were circulating in Paris yesterday did not clarify the situation. If anything they muddled it further. The front-runners, according to Le Monde, were: Philippe Seguin, president of the national assembly, a partially recanted EMU-sceptic, who would like to push government policy to the left; and Edouard Balladur, the former prime minister, a convinced EMU-fanatic, who would like to push government policy to the right.
Either appointment would amount in itself to several helpings of humble pie for Mr Chirac. Mr Balladur, an old friend, opposed him for the Presidency in an exceptionally rancorous campaign in 1995. Mr Seguin has been an irritating background critic of the Juppe government, who scarcely hides his low opinion of President Chirac's political abilities. The alternative, it is said, might be some technocratic figure from a nationalised or semi- state enterprise.
The favourite among centre-right parliamentary candidates of the Gaulllist RPR, and their partners in the UDF, would probably be Mr Seguin. He is seen as a man who could clarify the muddle in French politics by bringing government policy away from its market and EU-oriented reforms and back towards a dirigiste consensus. How this would square with France's commitments to prepare its economy for entry to the single currency is unclear.
Mr Balladur made his own pitch to regain the job in an interview with Le Monde yesterday in which he said the secret was not to follow the "Anglo- Saxon model" but to invent a liberalism "a la francaise".
Le Monde joined in the chorus of disapproval from the left of the manner and timing of Mr Juppe's departure. The newspaper praised the outgoing prime minister's determination in trying to push through unpopular reforms of the French welfare state. But it lashed Mr Chirac for cynically ditching him in adversity and said the President was now himself the object of a national "crisis of confidence". Left-wing politicians said the departure of Mr Juppe was a symptom of the "desperation" of the centre-right and created a constitutionally unfortunate precedent.
Will it succeed in saving the election for the centre-right? Possibly, but the arithmetic remains complex. Of the 555 constituencies in France proper, 400 are virtually certain to split evenly between the centre- right and the left. Of the others as many as 100 are too close to call.
Some 78 constituencies are three-way battles between the left, centre- right and far-right National Front. All but five of these were held by the outgoing government. The presence of an NF candidate, splitting the overall vote for the right, is expected to bring in a Socialist or Communist in at least 50 of these constituencies. The rest are too close to call.
The outcome on Sunday will depend on three variables: how many centre- right non-voters from last Sunday turn out to block the left; how many NF voters swing to the centre-right; and how many leftist non-voters, encouraged by the good showing of the Socialists, join the battle.
Diane Coyle, Business, page 18