Much of the uncertainty about the outcome of the French elections can be blamed on or credited to Charles de Gaulle. Seeking in 1958 to put an end to the revolving-door regimes of France's postwar period (26 different governments in twelve years), he scrapped proportional representation.
In its place De Gaulle introduced the country's unusual two-round electoral system. Basically the system is designed to winnow out fringe-party candidates in the first-round vote, so that only larger parties survive for the second round.
In theory and so far in practice the parties that win Round 2 command broad enough support to form...