It is the run-off in regional elections in France with indications that the turn out is around 60 percent – an approximate 10 percent rise from the first round.
The poll will show whether France’s far-right National Front can turn popularity into power.
The party came top in the first round and is leading in six of 13 regions in mainland France. Tactical voting could scupper their chances of outright victory.
Leader Marine Le Penn is standing in the north of the country. The second round has traditionally acted as a brake on the FN.
Commentators believe these results will show what position the party now occupies in French politics after support surged in the wake of the refugee crisis and the Paris massacre.
The run-offs are also seen as testing the waters for the 2017 presidential elections.
Opinion polls ahead of the ballot showed the centre-right Republican opposition of Nicolas Sarkozy gaining ground. They pushed the ruling Socialists into third place in the first round.
The Republicans could benefit after the Socialists removed losing candidates from vulnerable seats to avoid splitting the anti-FN vote. They urged their supporters to back Sarkozy’s conservatives.
President Hollande, who voted in his electoral home base in southwest France has seen his approval ratings surge more than 30 percentage points to 50 percent after his government’s response to the Paris attacks.
But it has so far not translated into greater approval for his party.
French regions have wide powers over local transport, education and economic development.