John Lichfield: Walk the streets of Paris to see how polarised France is

My pedestrian commute from office to home takes me up the Champs-Elysées and through the tourist tunnel beneath the Arc de Triomphe. Most evenings, I come across two forms of street theatre which symbolise the parallel, non-communicating universes of 21st-century France.

The other night the two universes briefly collided, giving me a scary insight into Marine Le Pen's popularity and why her far-right party may score a symbolically important success in local elections tomorrow and next weekend.

Street theatre, No 1. Each evening at this time of year, there is a service for military veterans beside the tomb of the unknown warrior below the Arc. Scores of provincial veterans, and their wives, are bussed into the capital to parade their flags and listen to military bands playing the "Marseillaise". After the service, the provincial veterans stand around at the exit to the Arc tunnel holding their rolled-up banners and wearing their berets and medal-encrusted, black or green blazers.

Street theatre, No 2. At that precise spot, on most days, half a dozen young men from the dreaded banlieues (multiracial suburbs) put on a breathtakingly athletic display of "hip-hop" acrobatics or breakdancing. They spin on their heads like tops. They support themselves on one hand while waving their legs elegantly to the tune of their tuneless music.

Each evening, crowds of Chinese, Japanese, Americans, Russians, Brazilians, assorted Europeans and even one or two Parisians gather to screech and applaud. Young Roma women in colourful skirts weave in and out of the crowd trying, unsuccessfully, to beg. Somali and Ivorian street hawkers stand nearby, trying, unsuccessfully, to sell three plastic, illuminating models of the Eiffel Tower for €1.

The other evening the multinational crowd of dancers, tourists, beggars and hawkers was so large that it engulfed the elderly men in black and green blazers. The old men and their wives looked around in bewilderment or indignation. The tourists looked straight through them. There was no violence. There were no arguments.

Most of the men were in their seventies or eighties and, therefore, veterans of the colonial wars of the 1950s and 1960s. They had come to Paris to remember lost comrades and to celebrate their sense of patriotism and Frenchness. And yet it was they, the provincial French veterans, not the breakdancers, or the tourists, or the hawkers or the Roma gypsies, who looked, and felt, like visitors from outer space in the centre of the French capital.

I detest the National Front, even in the form of low-octane, smiling intolerance practised by Marine Le Pen. All the more reason, therefore, to be scared by my glimpse, on a sunny evening on the Champs-Elysées, of the well-springs of her popularity. Her message, stripped of her father's anti-Semitism and Vichy sentimentalism, is simple and powerful: we, the real French, no longer feel at home in France.

Despite his efforts to strut the world stage as Libyan bomber-in-chief, President Nicolas Sarkozy faces humiliation in local elections tomorrow and next Sunday. In most years, the race for 2,000 seats on 100 departmental, or county, councils would be of interest mostly to political junkies. Not this year. The collapse of support for Mr Sarkozy's centre-right party and the surge of support for Marine Le Pen have turned the election into a laboratory for an unstable new era in French politics.

How will supporters of Mr Sarkozy's party, the Union pour un Mouvement Populaire (UMP), vote in the second round next week if faced with a run-off choice between the left and Ms Le Pen's National Front? Polls suggest that up to 160 of the local contests, mostly concentrated in Provence and the industrial north west, could be left hanging in just this way after the first round tomorrow.

Several recent national opinion polls suggest that this is precisely the dilemma which could confront voters for the "traditional" or moderate right in the second round of the presidential elections in 14 months' time. A first poll two weeks ago showing Ms Le Pen in the lead has generated a backlash of support for the left. The latest polls suggest that President Sarkozy will be knocked out in the first round in April 2012, leaving a two candidate run-off between Marine Le Pen and a Socialist contender, probably the former finance minister, Dominique Strauss-Kahn (now head of the IMF).

In such circumstances, would centre-right voters join a "Republican pact" to reject the National Front, as left-wing voters did when voting massively for Jacques Chirac against Jean-Marie Le Pen in the second round in 2002?

Faced with a "local" preview of this dilemma, some chieftains of Mr Sarkozy's UMP are reacting with panic and even hysteria. Moderate ministers have suggested that the UMP should – for moral and tactical reasons – ostracise the NF and recommend a second round vote for the left next weekend.

Other figures in the party cannot stomach the idea. To them, the "real" fault-line in French politics comes not between the NF and the Republican "mainstream" but between the right and the left. Officially, the UMP will make no recommendation to voters in local run-offs which match the NF against the left. De facto, some parts of the UMP, and the government, are already sounding like Ms Le Pen. Claude Guéant, Mr Sarkozy's former chief of staff, now his lugubrious, hardline interior minister, said last week: "Because of uncontrolled immigration, [the French] sometimes have the feeling that they are no longer in their own home." This is NF language. Earlier, he said: "The French are not xenophobes but, all the same, they want France to remain France."

Fair enough. But what do you mean by "France", Mr Guéant? The talented breakdancers on the Champs – Arab, African and white, just like the France football team – are just as much a part of 21st-century France as the all-white provincial veterans. France faces a deeply unpleasant presidential campaign. The argument will be two versions of national identity: "simple" and backward-looking, and "complex" and forward-looking. Since "simple" is easier to sell, Mr Sarkozy wants to wrestle ownership from the hands of the NF.

And yet who would not feel sorry for the bewildered old men on the Champs Elysées?