PARIS — Voting started in France on Sunday to elect thousands of local councillors in a test of the far-right National Front's growing hold on grassroots politics. Marine Le Pen's anti-immigrant, anti-euro FN party is banking on building a base of locally elected officials to become more mainstream and target national ballots. While it came second in the election run-up last week, in a setback to its claims that it has become the country's first party, the FN did win one in four votes and is all but certain to see a big jump from its current two councilors. “The FN is now implemented nationwide, it has reached a level that is high, too high,” Socialist Prime Minister Manuel Valls, who has been stressing his “fear” of the FN's rise to try and mobilize disillusioned left-wing voters, told Le Journal du Dimanche weekly. The second round is also a key test for ex-president Nicolas Sarkozy, who put a faltering comeback back on track by steering his conservative UMP party to an unexpected first place in the first round. But he needs a big win on Sunday to help consolidate his leadership of the UMP and get its nomination for the 2017 presidential election. Opinion polls see the UMP and its allies winning nearly twice as many seats as President Francois Hollande's Socialists and its partners. While surveys see the Socialists losing 20 to 40 of the 61 “departments” they now hold, the government, encouraged by signs that the economy is starting to turn around, will press ahead with reforms and a reshuffle is not in the cards for now, Valls told the Journal du Dimanche. The FN saw eight of its candidates elected in the first round and 100-220 more could be elected on Sunday, an Ifop poll showed. The far-right party is hoping to win one or two departements at most due to unfavorable electoral arithmetic but eyes a bigger win in regional polls later this year. Opinion polls see Le Pen likely too make it to the second round of the presidential election in 2017, but not winning. The complex election system, in which a duo of councilors is elected per constituency and they then vote to decide on 98 “departements” assemblies' presidents, means much negotiation will follow to see how many “departements” each party has won. In total, 4108 councillors with limited powers over roads, schools and social services will be elected. — Reuters