PARIS - France's far right National Front won more support than any other party in the first round of regional elections Sunday, according to polling agency projections, in a new boost for Marine Le Pen's anti-immigration strategy and a new blow to President Francois Hollande's Socialists.

The projections put National Front candidates on top so far in six of France's 13 newly drawn regions. But Sunday's voting was only a first round, and some mainstream voters may steer away from far right candidates in the decisive Dec. 13 runoff.

The elections took place in an unusually tense security climate just over three weeks after deadly attacks on Paris - a climate expected to favor conservative and far right candidates. It is the last election before France votes for president in 2017, and a gauge of the country's political direction.

Voters are choosing leadership councils for the regions, and had the choice of several parties in the first round. Polling agencies Ifop, OpinionWay, and Ipsos projected that the National Front won between 27 and 30 percent support nationwide.

The polling projections estimated the percentage of votes for different parties, not the number of seats they are expected to win on France's regional councils. The number of seats will be determined in next Sunday's runoff, which pits the leading parties in each region against each other.

Sarkozy's conservative Republicans party and its allies were projected to come in second place in the national vote at around 27 percent. The Socialists, who currently run nearly all of the country's regions, were projected to come in a weak third place, with between 22 and 24 percent, followed by a smattering of mainly leftist groupings.

The big question for the runoff is whether supporters of Republican, Socialist, and smaller candidates will rally together to keep the National Front from winning control of any of the regions. The party, long considered a pariah, has never had such significant political power.

The National Front is hoping the regional elections will consolidate political gains Le Pen has made in recent years, and strengthen its legitimacy as she prepares to seek the presidency in 2017.

The National Front "is the only [party] that defends an authentic French republic, a republic with only one vocation: the national interest, the development of French employment, the conservation of our way of life, the development of our tradition and the defense of all the French," Le Pen said Sunday night in Lille.

The Islamic State-inspired Paris attacks on Nov. 13 that killed 130 people and a Europe-wide migrant crisis this year have shaken up France's political landscape.

The arrival of hundreds of thousands of migrants in Europe and the exploits of IS have bolstered the discourse of the National Front, which denounces Europe's open borders, what it calls the "migratory submersion" and what it claims is the corrupting influence of Islam on French civilization.

Le Pen is campaigning to run the northern Nord-Pas-de-Calais-Picardie, which includes the port city of Calais, a flashpoint in Europe's migrant drama. Her niece, Marion Marechal-Le Pen, is running to lead the southern Provence-Alpes-Cote d'Azur region.