Will xenophobia go mainstream in French politics?

NF leader Marine Le Pen and NF candidate Gilbert Collard (Reuters)

The Rhône delta is a country of big skies, white horses, black bulls, pink flamingos, high unemployment and confrontational politics. It is also a man-made landscape of ancient embankments or digues (dikes) which tame the river Rhone and prevent it from inundating the beautiful flatlands of the greater Camargue. This weekend the dikes of the Camargue and adjoining areas are threatened with collapse: not the dikes enclosing the many channels of the Rhone but the political, and moral, barriers that have traditionally separated the xenophobic far right from mainstream French politics and especially the centre right.

"The system is cracking. You can feel it is cracking up wherever you go," Gilbert Collard told i after a histrionic speech to a National Front (NF) village meeting in Beauvoisin in the Petite Camargue.

Mr Collard is a 64-year-old celebrity lawyer. He has a mane of grey-brown hair, a rumpled blue jacket and an open shirt. He is the National Front candidate in this part of the Gard département – and one of four or five far-right candidates who have a chance of winning a seat in the second round of parliamentary elections this Sunday. Mr Collard may be right. The landscape of French politics could be transformed this weekend.

President François Hollande's moderate left will win a parliamentary majority but there is nothing especially surprising about that. The sub-plot of the elections is more gripping, and scarier, than the main-plot.

Will the far right win any seats? Will centre-right voters and even centre-right politicians break ranks with their leadership and support a party that has for years been decried as beyond the pale of France's "Republican values" of liberty, equality and fraternity?

On Sunday, there will be 29 "triangular" contests (out of 577) because NF candidates qualified in the first round to compete with candidates of both the centre left and centre right. There will be a handful of contests in which far-right candidates will face a single opponent of the left (including the NF leader Marine Le Pen, who has a good chance of winning in the Pas de Calais).

The biggest concentration of the surviving NF candidates is here in the south and especially in an arc along the Languedoc coast, through the Rhône delta and into the Alpine foothills. Why here? Mr Collard harangued a pliable jury of NF voters in the Beauvoisin village hall. On the balcony of the house opposite, a woman of Arab origin in an orange dress quietly smoked a cigarette in the evening sunshine.

In the south, immigrants and people of immigrant origin do not live just in urban areas. In Beauvoisin (translation "beautiful neighbour") one in every three people is of foreign origin.

Katy Guyot, the Socialist candidate in this constituency, says there has been a drum-beat from local far-right politicians for years identifying ethnic minorities with crime, unemployment, "incivility", welfare dependency and a decline of patriotic values. Many centre-right politicians now campaign on almost exactly the same themes.

The main centre-right party, the Union pour un Mouvement Populaire (UMP) has moved towards the NF. Marine Le Pen has moved, at least cosmetically, towards the UMP. The core NF appeal remains a kind of white tribalism and fear of Arabs and Islam. All the same, since she replaced her father as NF president in January, Ms Le Pen has pushed openly racist, anti-Semitic and thuggish elements out of the party. It is Ms Le Pen's ambition to broaden her movement.

She has even talked of renaming the party – something that infuriates her father, Jean-Marie Le Pen, and other NF diehards. The complex rules of the two-round parliamentary elections have created this week a series of live experiments in Ms Le Pen's ambitions.

The Socialists, Greens and harder left have long made deals to maximise parliamentary seats by standing down for one another in the second round of parliamentary elections. The UMP and its predecessors have always refused to make such deals with the NF. Officially, the UMP has held to that position this week. In practise, the Maginot line between right and far right has been widely breached.

The former defence minister, Gérard Longuet, has spoken of the NF "no longer carrying a mark of Cain". Another former Sarkozy minister, Nadine Morano, has said that she shares many "values" with NF voters.

In a series of second round races – especially here in the south – there has been a bizarre, hesitation waltz between UMP and NF candidates. But in the end, manoeuvres and local jealousies apart, it will be centre-right voters who decide whether the dike between "traditional" and "far" right will crack this weekend. "Even with the UMP candidate running, I will win," Mr Collard said. "Half of the UMP voters feel closer to me than to the left. It will be close. But I will win."