France's far-right National Front (FN) has beaten its previous record in local elections by winning at least four towns, based on exit poll results.
FN candidates gained a total of nine percent of the vote in Sunday's runoff and looked set to secure the southern towns of Beziers and Frejus, amid public dissatisfaction with President Francois Hollande's Socialist Party.
The FN was also likely to win the eastern town of Hayange, the outgoing Socialist mayor there said. The party already made a breakthrough in last week's first round of voting by winning power in the northern town of Henin-Beaumont.
"Clearly we are entering a new phase, the duopoly of French politics has been broken and we must reckon with a third force," said Marine Le Pen, leader of the FN.
Sunday's runoff round of voting came after a week that saw French unemployment surge to a new record, making a reverse of first-round losses by the Socialists unlikely and a cabinet reshuffle possible as early as Monday.
Some 80 percent of the French want Hollande to dismiss Prime Minister Jean-Marc Ayrault, according to a Harris Interactive poll this week, and ambitious and tough-talking Interior Minister Manuel Valls is their favourite to replace him. Veteran Foreign Minister Laurent Fabius is also seen a contender for the job.
Despite the election losses, Hollande's government has said it will stick with economic reforms and spending cuts.
The next presidential and parliamentary elections are scheduled for 2017.