The victory of the French socialists in presidential elections last month would be a hollow victory if the country fails to elect a left-wing prime minister.
Hollande is forging alliances with the Greens and other moderate leftists. Another potential coalition partner is the Left Front, which brings together the Communist Party and Left Party.
The two-stage parliamentary ballot staged this, and the following, weekend will show whether Hollande's victory was truly an endorsement of his political vision or just an indictment against his predecessor Nikolas Sarkozy.
Al Jazeera's Paul Brennan reports from Paris.