2018 Val-d'Oise's 1st constituency by-election
28 January 2018 (first round)
4 February 2018 (second round) | |||||||||||||||||||||||||||||||||||||||||||||
| Turnout | 20.33% 27.76% (first round) 19.09% 20.51% (second round) | ||||||||||||||||||||||||||||||||||||||||||||
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The first round of a by-election was held in Val-d'Oise's 1st constituency on 28 January 2018, with a second round on 4 February because no candidate secured a majority of votes in the first round. The by-election was called due to the invalidation of the election of Isabelle Muller-Quoy, candidate of La République En Marche! (REM), in the June 2017 legislative elections by the Constitutional Council on 16 November 2017. It was the first legislative by-election held during the 15th National Assembly.
In the first round on 28 January, Isabelle Muller-Quoy of La République En Marche! and Antoine Savignat of The Republicans (LR) advanced to the second round, as they did in June 2017, with Muller-Quoy securing a considerably lower share of the vote amid low turnout. Savignat was elected in the second round with 51.45% of the vote, defeating Muller-Quoy.