If the first round were a reliable indicator, Socialist candidate François Mitterrand would have been elected president in 1974, when he scored a stellar 43%, not far from the 50% threshold that would have handed him the presidency with no need for more voting. In reality, he had to wait seven years to push Valery Giscard d’Estaing, a conservative, out of the Élysée. In 1981, when Messrs. Giscard and Mitterrand ran against each other again, Mr. Giscard’s first-round 3 percentage point lead on his competitor wasn’t enough to secure him a second mandate.

via blogs.wsj.com