French student groups, bolstered by a firm show of support from trade unions, led a new protest march Tuesday to ratchet up pressure on the premier to scrap a contested labor law.

Dominique de Villepin, meeting with ruling party lawmakers, expressed willingness to soften two provisions of the contested "first job contract" — but refused to consider canceling it altogether.

As he spoke, the fourth student-led protest in eight days began in the capital, with thousands marching across the Left Bank and shouting "It's the street that rules!" in defiance of Villepin.

The protests — at times violent — have become the biggest labor test for Villepin, and have highlighted challenges faced by many European governments looking to reform their job markets at a time of increasing globalization.

The boisterous debate could shape the outcome of next year's presidential and parliamentary elections. Villepin's popularity has plunged, and the Socialists have vowed to revoke the law if they return to power.

The jobs law, passed by parliament this month, is aimed at injecting flexibility into France's labor market and encouraging companies to hire young workers facing unemployment rates of more than 20 percent — twice the national average. Critics fear it will hurt job security.

It takes effect next month, and will allow employers to fire workers younger than 26 years old in the first two years of employment without giving a reason.

Bernard Accoyer, who heads the ruling UMP party in parliament's lower house, said Villepin was flexible about how companies apply the two-year trial period and said corporate human resource advisers should obtain explanations from employers when young workers are fired.

Villepin, who appears to be staking his political career on the issue, sought to rally the party as critics from right and left increasingly called for it to be sharply modified or withdrawn.

Attention also focused on the fate of a protester in a coma after violence erupted in a protest Saturday in Paris. Union leaders claimed the 39-year-old man had been "violently trampled by a police charge," but a top police union official said demonstrators had struck him.

"The entire country has plunged into a test of power, which can become very serious," Jean-Marc Ayrault, the Socialist leader in the National Assembly, told the lower house in a weekly session. "There is a protester between life and death, and we demand the truth."

Majority lawmakers dramatically quit the chamber after Ayrault claimed that Villepin was driven by "egotism," many shaking their fists and shouting "CPE" — the French acronym for the jobs contract.

Students have blockaded dozens of universities across France, sparking pockets of dissension among some students who want to continue their studies.

Overnight, hundreds of students occupied a prestigious Paris graduate school of social sciences, known as EHESS, but the situation was calm and police were not called in, said school president Daniele Hervieu-Leger by telephone.

About 300 other students, frustrated by the paralysis of their schools by protesters, staged a "counter-demonstration" outside Paris' famed Pantheon — not far from the protest march. They chanted "Enough, enough! Let us through!"

Courts have begun intervening. A tribunal in southeastern France late Monday ordered an end to one such blockage in the Alpine city of Grenoble, ruling that every student found occupying any of the three city universities could face fines of $60 a day starting Thursday.

Many student protesters were emboldened by a call Monday by trade unions for a national day of strikes for March 28 to protest the jobs plan. The strike could affect sectors from travel to heavy industry to schools, though more details were expected in coming days.

High school students were increasingly taking part, with their leading association, UNIL, claiming Tuesday that one in every four high schools in the country was blocked by protesters.

Another day of nationwide student street protests is planned Thursday.