Marine Le Pen can breach her glass ceiling: The drastic effect of differentiated abstention

Abstract

Ranges of differentiated abstention are shown to reverse an "exact" poll estimate on voting day allowing the minority candidate to win the election. In a two-candidate competition A and B with voting intentions at $I_a$, $I_b=1-I_a$ and respective turnout at $x$ and $y$, there exists a critical value $I_{ac}$ for which $I_{ac}<I_a<\frac{1}{2}$ yields an actual election outcome $v_a>\frac{1}{2}$. The reversal may occur without any change of individual choices. Accordingly, for a set of turnouts $x$ and $y$ the minimum voting intention $I_{ac}$ required for A to win the final vote can be calculated. The various ranges of $x$ and $y$ for which $I_{Ac}$ is smaller than the expected 50\% barrier are determined. The calculations are applied to the coming 2017 French presidential election for a second round scenario involving the National Front candidate Marine Le Pen against either the Right candidate Fran\c{c}ois Fillon or the Center candidate Emmanuel Macron. Several realistic conditions are found to make Marine Le Pen win the election despite voting intentions about only 40-45\%.