A candidate from the UMP conservative party narrowly beat a far-right rival to win a by-election in southwestern France on Sunday, squeezing Socialist President Francois Hollande's parliamentary majority to just three seats.
The UMP's Jean-Louis Costes claimed victory as partial results showed him winning the runoff vote with 53 percent, yet a strong score of 47 percent by National Front candidate Etienne Bousquet-Cassagne underscored a surge in populist sentiment as France grapples with record unemployment.
The ruling Socialist Party lost the seat when a minister quit his post over a Swiss bank account scandal. Its candidate to replace him was knocked out in a first-round vote a week ago, in a blow to the increasingly unpopular Hollande.
Both Bousquet-Cassagne and National Front Vice President Florian Philippot hailed the anti-Europe and anti-immigrant party's score as an ideological victory.