French trade unions have set a deadline of mid-April for the government to withdraw a controversial youth labour law designed to tackle unemployment.
The ruling UMP says there will be no limits on Wednesday's talks
Otherwise, the unions said, they were ready to organise a "new day of action" along with student groups.
Union leaders began a meeting with governing party officials on Wednesday to press their demands.
Hundreds of thousands of people marched across France on Tuesday in the latest of a series of rallies.
Critics say the First Employment Contract (CPE) law makes it easier for employers to dismiss young workers. They also say it undermines traditional job protection.
The government argues the law is needed to reduce high youth unemployment.
Protesters have given President Jacques Chirac until the start of parliament's spring recess on the Easter weekend to withdraw the controversial law creating the CPE or face more strikes and protests.
A joint statement for protesting groups said they were "ready, unless there is a rapid decision to withdraw the CPE, to decide on a new day of action".
FIRST JOB CONTRACT
Contrat Premiere Embauche (CPE): A new work contract for under-26s allowing a two-year trial period
In that period, employers can end a contract without explanation
After two years, the CPE reverts to a standard full-time contract
Became law on 2 April, but amendments are expected - employers are being asked not to apply it yet
The head of the main CGT union, Bernard Thibault, said he would not give up until the law was repealed.
Millions of people have taken to the streets across the country in a series of protests against the law, which came into force on Sunday.
The government has made a number of concessions, including asking French employers not to use the contract until amendments are made.
On Friday, President Chirac pledged to shorten the period in which young people could be fired from two years to one and said employers would need to give a reason for dismissal.
Trade unions say the proposed amendments are unacceptable.
But Laurence Parisot, head of the Medef employers group, said on Tuesday that the protests were posing a threat to the economy.
Interior Minister Nicolas Sarkozy, leader of the ruling centre-right Union for a Popular Movement (UMP), is chairing Wednesday's talks.
The party has already signalled further possible climb-downs.
"We'll be ready as of [Wednesday] to receive the unions, to listen to them. There won't be any limits to the talks," UMP parliamentary chief Bernard Accoyer said.