A day after more than a million people joined one of the biggest protests of recent French history, union leaders urged Jacques Chirac to use his powers to stop the controversial measure, which was voted through parliament two weeks ago and is waiting to pass into law.
They called on Chirac to send legislation back to parliament stripped of the First Employment Contract, CPE.
In a letter to Chirac, France's five biggest unions urged him to order a fresh reading of the law, without youth job contract measures which allow employers to sack at will workers under 26 at any stage in a two-year trial period.
"We ask you, Mr President, to appreciate how much the current crisis is a source of exasperation and tensions in the country," they wrote.
Aides said Chirac, who cancelled a trip to Le Havre planned for Thursday to stay in Paris and monitor the crisis, would speak out in the coming days.
Hire and fire
An announcement from the Elysee Palace early on Wednesday said that Chirac will speak publicly on the CPE soon, but it did not say when or give any indication of which way he is leaning.
The proposed measure will make it easier for French employers to hire and fire young people.
But Philippe Douste-Blazy, the foreign minister, played down chances the law would be re-written.
Chirac has cancelled a trip to Le
Havre to monitor the crisis
"One possibility is to send the law back to parliament. Do the president or the prime minister want this? I don't think so," he told international news organisations at a breakfast.
Until now the 73-year-old president has been discreetly supportive of Dominique de Villepin, the embattled prime minister, whose fight to introduce the CPE has left him increasingly isolated.
On Tuesday, in the largest wave of protests so far, unions said up to three million people took part in demonstrations - three times the police estimate.
Almost 800 youths were arrested in sporadic violence that marred some protests, notably in Paris, where police used tear gas and water cannons to quell unrest.
Students in Rennes in western France continued their action on Wednesday, blocking three main roads out of the town.
Conceived by Villepin to loosen the labour market and bring down youth unemployment, the CPE has provoked a massive backlash from the political left - with an alliance of unions, student groups and political parties coordinating three weeks of escalating protests.
The prime minister says the new law would help cut youth unemployment of close to 23%, but critics say it will create a generation of disposable workers.
Villepin is also under intense pressure from Nicolas Sarkozy, France's interior minister, UMP leader and a likely rival for 2007 presidential elections, who has urged him to compromise.
Villepin says the law will help cut
numbers of unemployed youth
"In 2006, when there is a misunderstanding, you have to make a compromise. There is no shame. It is not a swear word. A real negotiation should take place, without pre-conditions," he told the daily Le Parisien.
Villepin has vowed to see the CPE into law, offering only "adjustments" on its two most contentious provisions: the two-year trial period, and the free hand given during that time to employers to fire under 26 year-olds.