Not a great answer I'm afraid, but in the first elections for the French constituent assembly in 1945, the Parti communiste français took 153/586 seats; considering this was a proportional representation election, the PCF managed to take the 2nd highest number of seats. In the second election six months later, the PCF won 182 seats - the most won by any party. In the 1951 elections, PCF came third, in the 1956 election they came first. But after the Fifth Republic, PCF's power declined.

Communism has always been popular in France; the PCF is still Europe's largest and most influential communist party (other than the KPRF.)