What does it mean to be "mormon de gauche" (leftist mormon) in France?
First you must keep in mind that the political spectrum is much wider in France, from neo-trotskyist far left to monarchist far right. And it is also wider among French Saints than among their US church fellows – even though extremists of both sides are quite rare in the Church.
Another major difference is that the "moderate" left and right in France are more left than their US counterparts. Many positions considered "leftist" in the US are here quite consensual across the French political chessboard. Socialized medical insurance, legal abortion, civil union for gays, right of strike, separation of church and state (among many others) are accepted by the moderate rightist parties. This is why the moral issues (abortion, gay rights) are not considered by French Saints as politically deciding.
Another point to consider, in spite of a largely accepted separation of churches and state, is the strong, traditional ties between the French conservative parties and the Catholic Church, which represents about 85% of the population. This makes many Saints uncomfortable when dealing with the conservative parties. For instance, they are shocked when president Sarközy (a conservative) addresses the pope in public as "très saint père" (most holy father).
All those reasons explain why a bigger proportion of Mormons in France vote for leftist parties or are involved in workers unions than in the US.
This said, it is hard to find which proportion of French Saints are leftists. The first reason is that two subjects in France are not usually brought up in conversation, including by church members: money and politics. When two French people speak together, they most likely talk about cooking!
Another reason is that the Church is perceived by the French Saints as "conservative". Even though the Church remains strictly neutral on political issues, the overwhelming strength of the Republican vote among US saints is well known here. The problem is that many Mormons here consider their brothers from across the ocean as models. This is why some might feel "out of standard" - if not "guilty" - for leaning to the left, and keep quiet about it.
Once two or more "mormons de gauche" have identified each other as such, they talk more freely of political issues. From such conversations I've had so far, it seems that there is not much difference between them and other French leftists. All those I know (including myself) strongly supported Chirac (even though he was a conservative) in his adamant opposition against the war in Iraq. They opposed the recent return of France into NATO military commandment. They consider Sarközy as a dangerous sorcerer's apprentice who is endangering the "French social model" which has existed since the end of World War II. They would like the government more involved in the economy, especially to restrain the immorality of wild capitalism. They support the European Union as an instrument of peace but reject its dogma of unrestrained economical competition. They want strong public services (education, electricity, railways, etc.) and don't want them to be dismantled and sold to private operators. They want a better protection of environment. And last but not least, they are saddened by the "war of the chiefs" that weakens the Socialist Party (second party in the country and main party of the moderate left).