Polls suggested that Le Pen's party had some momentum, with legitimate ambitions to win control of leadership councils in one or more of France’s 12 mainland regions.
A decisive, second round of voting in France's regional elections is being scrutinised as a litmus test of whether the anti-immigration far right is gaining in acceptability before the French presidential election next year.
Marine Le Pen, leader of the far-right National Rally, has spent a decade trying to cast off the extremist reputation that made the party anathema to many French voters in its previous guise as the National Front.
A failure to win control of a region Sunday would mark a stinging setback for the rebranded party.
There were plenty of hand sanitiser bottles but not many voters at a polling station in Saint-Quentin in northern France as elections went under way.
Paris voting stations that sometimes see lines stood largely empty, other than a few elderly voters. Turnout nationwide was less than 13 percent by midday.
A record-low turnout of 33 percent in the first round of voting on June 20 had proved particularly damaging for the National Rally and Le Pen's hopes of securing a regional breakthrough to bolster her 2022 presidential campaign. The party has not previously won a region.
Polls had suggested that Le Pen's party had some momentum, with legitimate ambitions to win control of leadership councils in one or more of France’s 12 mainland regions.
But the apathy last week also infected National Rally voters. Only in one region, in the southeast, did the party finish first. Its candidates elsewhere were all relegated to second place or lower, with some openly abandoning all hopes of winning in round two.
A major question in the runoff is whether voters will band together to keep Le Pen's party out of power as they have in the past, repulsed by her anti-immigration and anti-European Union populism and the racist, antisemitic image that clung to the National Front, which was founded by her father, Jean-Marie Le Pen.
The party dominated the first round of the last regional elections in 2015 but collapsed in the runoff as parties and voters joined together against it.
The National Rally's best chance of a first-time regional victory is in the southeastern Provence-Alpes-Cote d’Azur region. Its candidate there, Thierry Mariani, is in a tight race with a mainstream conservative incumbent, Renaud Muselier.
Results are expected after the last polls close at 8 pm. The left currently heads five of the 12 mainland regions while the mainstream right runs seven.