Thousands of civil servants demonstrate along a boulevard in Paris. Civil servants, from teachers to postal workers, began a mass walkout across France on Tuesday, the seventh day of a transport strike that has caused havoc on French rails.

Paris ? President Nicolas Sarkozy stood firm against spreading strikes Tuesday, insisting he will not water down plans for a thorough overhaul of France, even as civil servants joined the walkouts and thousands of protesters took to the streets.

Sarkozy was characteristically defiant as he broke what had been an unusual silence during a week of transit strikes that have disrupted travel across the nation. He accused the strikers of holding commuters “hostage” and called for them to return to work.

Turning to critics who hope he can be forced to back away from deep economic, social and political changes for a country that has proved difficult to reform, Sarkozy had a simple message: Forget it.

“France needs reforms to meet the challenges imposed on it by the world,” he said in a spirited speech to mayors. “These reforms have been too long in coming. … After so much hesitation, so much procrastination, so many backward steps, we will not surrender and we will not retreat.”

Sarkozy appears to have the upper hand in his test of strength with powerful transport unions fighting tougher pension rules – opinion polls say the public strongly supports the president, and strikers have been trickling back to work on subway and long-distance trains.

If he wins the faceoff, Sarkozy will improve his chances for pushing through even bigger and more ambitious reforms. One involves slimming down and reforming the civil service, whose 5 million workers make it France’s largest employer.

Sarkozy insisted in his speech that he didn’t deliberately pick the fight with the train unions.

But he certainly chose the field of combat well: Pension rights that train drivers and other specially classed workers are fighting to protect are cushier than those enjoyed by most in France. Sarkozy says pension rights should be equal for all – and he has public opinion on his side.

Sarkozy “hasn’t won the gamble yet because the trains still aren’t running. But it seems he will win,” said Etienne Schweisguth, a researcher at the respected Sciences Po school of political sciences in Paris.

The question now is when and how the transport strike, which was heading into its eighth full day today, might end.

Talks with transport unions were to start today, and the government said state representatives would take part.

Transport workers are not Sarkozy’s only challenge.

Hundreds of thousands of civil servants – teachers, customs agents, tax inspectors and others – stayed off the job Tuesday to press their separate demands for pay raises and job security. That walkout closed schools and caused flight delays.

The double whammy of transport and public service walkouts further frayed tempers. In the Paris Metro, one young man cursed, “Even the escalators are on strike,” when the equipment ground to an unexplained halt at one station.