But in 1986, a former lieutenant who fought for a French Algeria became Prime Minister: Jacques Chirac. As it happens, Mr. Chirac is also the presidential candidate of the neo-Gaullist Rally for the Republic.

''To reconcile France with its colonial past is to reconcile France with itself,'' Mr. Chirac declared to pieds-noirs in Nice last month. ''As a lieutenant in Algeria, I did my duty. I shared your hopes and your agonies, and understood your elan.''

Mr. Chirac has backed up his flattering words with a series of indemnization measures for the ex-colonists that have earned him the backing of one of their most active associations, a novelty for a Gaullist candidate. But the Prime Minister may attract fewer pied-noir votes than Jean-Marie Le Pen of the ultraright National Front. Would Expel Immigrants

A paratrooper in colonial Algeria, Mr. Le Pen is today the noisiest champion of expelling Arab immigrants from France. He has a considerable following here in Montpellier, a thriving city of 230,000, where every fifth inhabitant is pied-noir in origin.

A favored pied-noir hangout is the Cafe Riche, where Henri Arnavielle, president of a local association of former Algiers residents, and a few friends were having a midday pastis. A woman who declined to give her name gladly offered her political viewpoint.

''My grandparents left Alsace for Algeria in 1870 because they didn't want to become German,'' said the woman, referring to the German annexation of the province. ''And I left Algeria in 1962 because I did not want to become Algerian. I am voting for Le Pen.''

In the murky cross-currents of pied-noir politics, though, nothing is clear.

''You are discovering the politics of the Mediterranean!'' the Socialist Mayor, Georges Freche, declared as he signed a stack of documents on his desk. ''There are a lot of pieds-noirs who will vote for Le Pen in the first round and, without thinking about it, vote for Mitterrand in the second round on May 8.''