By Caroline Wyatt
BBC correspondent in Paris
"Bye Bye Raffarin" crows an editorial in the left-wing newspaper Liberation, which celebrates the return of France's left after its last two years out in the cold.
The newspaper hopes that first round of Sunday's regional elections may finally start to banish the left's lingering in-fighting and humiliation following the presidential elections of 2002, when the Socialists were beaten into third place by the centre-right Jacques Chirac and the far right's Jean-Marie le Pen.
Chirac is safe at the top, but he has suffered a setback
The French media are in no doubt that Sunday's results were a major blow to the credibility of the centre-right government of Prime Minister Jean-Pierre Raffarin and President Chirac.
The word "punishment" figures largely in Monday's headlines, with "le choc" (shock) in the centre-right Figaro.
So where did the government go wrong, and why did French voters apparently use these regional elections to protest against the national government?
If first round results for France's 22 regional councils are repeated next week - a 62% turnout, much higher than expected, giving 40% of the votes to the left, 34.5% for the centre right UMP and UDF, with 5% for the far left and 16.5% for the far right - that could give the left alliance control of more than half of the regions.
That in itself is no big deal, as the regional councils wield little real power.
But the sheer scale of the overall protest vote against the governing UMP does matter. Even though President Chirac is safely ensconced in office until 2007, his prime minister Jean-Pierre Raffarin will not be sitting comfortably.
Sarkozy (left) may not want the unpopular Raffarin's job
He has implemented Mr Chirac's deeply unpopular programme of reforms - cutbacks to France's generous welfare system, including pensions - while appearing unable to bring down unemployment, which is running at almost 10%, or kick-start the economy.
The centre of Paris suffers almost daily demonstrations, by dissatisfied intellectuals, scientists, teachers, health-care staff or blue-collar workers, while Mr Chirac's and his prime minister's popularity dwindle.
Mr Chirac may be secure in the Elysee Palace but a repeat of this Sunday's results in the final round next week could prove fatal for Mr Raffarin, who watched in disbelief as the Socialists look set to win his own former regional power-base of Poitou-Charentes, which he ruled for 14 years before becoming PM.
Mr Chirac could decide next week that Mr Raffarin should become the government's scapegoat for these results - leaving the man he plucked from the regions for his apparent ability to speak to ordinary people with little hope of a political future.
The government's reform plans have sparked a wave of protests
A cabinet reshuffle is widely tipped to happen after the next round, though Mr Chirac may hold back from sacking his prime minister because the alternatives could be far worse for the president.
One man tipped for high office is the relentlessly ambitious Interior Minister Nicolas Sarkozy - but he would like Mr Chirac's job, not Mr Raffarin's.
In the end Mr Chirac may be advised to wait until June and the European elections, to rid himself of his loyal if unpopular prime minister.
The 16.5% scored by the far right in France - Jean-Marie le Pen's National Front plus other regional extreme right parties - has aroused mixed emotions.
There is some relief that the Front did not score as well as Mr le Pen did in the second round of the 2002 presidential elections and that the far right is unlikely to take control of any French region.
But there is also discomfort for many in France that the extreme right seems to have consolidated its position as a real force in French politics, rather than proving a home for flaky protest votes.
The extreme right may not get into power in the regions this time round, but it could prove a king-maker in a handful of areas.
Its agenda is already creeping onto the national stage, as the centre-right UMP and UDF seek to neutralise the appeal of the far right's hard line on issues such as immigration and security.
The results next Sunday could mark a turning point for Mr Chirac's rule in France - and decide whether his government continues with its reforms, or slows them down to prove it is listening to the very clear message from the French people.