President Emmanuel Macron's fledgling En Marche! party has secured a large majority in parliamentary elections, exit polls suggest.
Macron's party, which didn't exist 14 months ago and offered novice candidates from civilian life, has drawn from left and right to fill its ranks, effectively blurring the traditional left-right political divide.
That prospect worries both rivals and some voters, and makes the turnout rate critical.
Far-right National Front leader Marine Le Pen registered a massive victory in her northern bastion of Henin-Beaumont, defeating Mr Macron's candidate as she won her first French parliamentary seat.
The center-right Republicans Party is expected to form the second biggest faction in the lower house.
Former President Francois Hollande was a member of the Socialists, who are projected to earn only a couple of dozen seats compared with 280 they now hold.
Le Pen said she would "fight with all necessary means the harmful projects of the government", especially what she called Macron's pro-European, pro-migrant policies.
Far-left ex-presidential candidate Jean-Luc Melenchon is voting in the Mediterranean city of Marseille, where he is seeking a seat as well. "We're going to find ourselves with fewer opposition representatives than there are in Russian Federation".
Turnout will be closely watched after it hit a near 60-year low in the June 11 first round of voting, leading some to warn Macron that his mandate is not as strong as he thinks.
With 82 percent of the votes counted, Macron's party had 42 percent of the vote, the conservative Republicans 22 percent, the far-right National Front 10 percent and the Socialists only 6 percent. His centrist Republic on the Move! party is expected to win more than 400 seats.
Le Pen, who entered parliament for the first time in her career, told supporters her FN had won at least six seats - but the party was certain to fall short of its target of 15 seats.
The National Front had two seats in the outgoing parliament and the only lawmaker seeking to renew his mandate, Gilbert Collard running in the southern Gard region, could lose.
Prime Minister Edouard Philippe, a center-right politician who joined Macron's movement, said "through their vote, a wide majority of the French have chosen hope over anger".