President Nicolas Sarkozy faces a crucial test of his nerve today as a transport strike continues into its seventh day of commuter chaos, and civil servants stage a walkout that could see up to half of France's schools closed and disrupt air traffic control, the postal service and even weather forecasts.

France's rail and bus strike is continuing despite trade union leaders agreeing to begin talks with the government and state employers tomorrow. They are protesting at plans to change special pensions deals which allow certain workers to retire as young as 50 on favourable terms.

But the strike has been prolonged to overlap with Sarkozy's latest industrial headache: an unrelated 24-hour stoppage by public sector workers, including teachers, hospital staff and postal workers. State employees from defence ministry secretaries to weather office staff will stop work in protest at low salaries and public sector job cuts. But the president is said to be standing firm on his modernising agenda, in the face of a "black November" of protests against his reforms.

Sarkozy's senior adviser on industrial relations, Raymond Soubie, insisted that this week's snowballing strikes were not the president's "Thatcher moment". He said the transport workers' pension deals would be reformed, but added: "Sarkozy has not wanted to force it through à la Thatcher, but through dialogue."

Sarkozy, despite his image as an iron-willed moderniser, has so far taken a cautious and soft approach. Unusually for the omnipresent leader dubbed "super Sarko", he has not made a public speech for almost a week, aware that he must not be seen to be crowing victory or humiliating his opponents.

Today the president will address a congress of mayors and is expected to break his silence to explain his reforms to the nation. His opinion poll ratings, though still positive, are slipping, sounding the end of his post-election state of grace.

The striking civil servants' grievances are two-fold. They argue that their salaries are so low that they cannot make ends meet. The issue of "purchasing power" - low salaries that cannot match the rising cost of living - is currently the key concern of the French public. Sarkozy promised to kick-start the struggling economy, but the public complain that they have yet to see an improvement in their purses.

Public sector workers are also protesting against one of Sarkozy's key reforms - his "civil service revolution" to cut the unwieldy state bureaucracy and public administration, the costliest in Europe. Around 5.2 million people work in the public sector, one fifth of the French workforce. Sarkozy has pledged to cut the numbers, starting by not replacing one in three who retire in 2008. This would see up to 23,000 jobs go next year, and at least 11,000 in education.

Gilles Moindrot, head of the SNUIPP union for primary school teachers, told the Guardian: "The French population is growing and to cut [the number of] teachers is incomprehensible. Next September we'll be looking at one teacher per 50 children. For a primary teacher aged 45, an average salary is around €2,000 (£1,400) a month; with the cost of housing, that's barely enough to live on."