Seldom have France’s opposition Socialists seemed in a more pitiful state. Overtaken long ago by the right, they were also being outflanked by the left last week as the public fell under the dubious spell of “the red postman”.

Olivier Besancenot, the charismatic postal worker from Neuilly, an affluent suburb of Paris, has emerged as an icon of the French left, whose growing popularity has been an embarrassment to the mainstream Socialist leaders. They met yesterday in the western port of La Rochelle for an annual “summer university” debate to help to find a new leader.

The fact that Besancenot, leader of the Communist Revolutionary League, was in the throes of establishing an “anticapitalist” party committed to toppling the French state did not seem to damp enthusiasm among the public. Polls showed the radical firebrand to be more popular than most of the Socialist leaders, and he is ranked as the “best” opponent of President Nicolas Sarkozy.

In Britain he might have had to make do with a soap box, but Besancenot, 34, embodies a very Gallic “down with the rich” mentality. This is, perhaps, a legacy of the revolution and helps to explain why droves of extremely wealthy French families are opting for exile in Brussels, Geneva or London each year.

“We’re not waiting for the next election to try to stop Sarkozy,” said Besancenot last week in a dig at Socialist leaders. They seemed to put more energy into feuding with one another than opposing the French leader’s programme of economic and social reforms.

The bickering has helped Besancenot to win new supporters, but his rise was also a reflection of French nostalgia for communist ideology long since discredited in the rest of the world.

At the same time Besancenot’s “anticapitalist party”, to be launched in January, is intended to appeal to a generation of young leftists inspired more by the antiglobalisation struggle than by the communist hammer and sickle.

Already he was won protestations of support from José Bové, the pipe-smoking antiglobalisation campaigner, and from Daniel Cohn-Bendit, the Green MEP and former leader of the May 1968 student riots. Arlette Laguiller, leader of another Trotskyist group and serial presidential candidate, has also signed up as a member of the new party.

“We want to be a credible alternative,” said Besancenot, a teacher’s son whose boyish air has led to comparisons to Tin-tin, the comic strip hero.

Despite the wholesome look – one observer described him as everybody’s “ideal son-in-law” – Besancenot is considered in some quarters as a dangerous revolutionary, quaint though his early-20^th-century rhetoric may seem. He has complained of being followed and bugged, presumably by the domestic intelligence service.

“It’s up to the population to get there one way or another,” he said, referring to the revolutionary goal recently on the French television equivalent of This Is Your Life. The class struggle did not have to be violent, he added, to the relief of a country forged in the shadow of the guillotine: “For me, the revolution is not a puddle of blood on each street corner.”

Sarkozy, who came to power on a promise of “rupture” with the bad ways of the past, has wrongfooted the Socialists, already demoralised after three consecutive losses in presidential elections, by recruiting some of their best assets to serve in his government. Union leaders also appeared to have lost their teeth after being wined and dined by Sarkozy.

Besancenot has stuck to his guns and appears to be reaping the rewards. One poll last week gave him an approval rating of 47%, way above François Hollande, secretary-general of the Socialist party (31%), and Ségolène Royal, the latter’s former companion and also the Socialist presidential candidate who was defeated by Sarkozy last year (35%).

Compared with the deeply split Socialists, Besancenot’s anticapitalist grouping seems harmonious, but he has come under attack from some of the comrades for being a darling of the media. He defends himself by saying that appearing on television chat shows helps him to communicate his message better.

The criticism of him just goes to show, as Le Figaro newspaper put it, that in France “there is always someone to the left of you”.