France faced a hung parliament and deep political uncertainty after the three main political groups of the left, center and right emerged from snap legislative elections on Sunday with large shares of the vote but nothing approaching an absolute majority.

The preliminary results upended widespread predictions of a clear victory for the National Rally, Marine Le Pen’s anti-immigrant party that dominated the first round of voting a week ago. Instead, the left-wing New Popular Front won 178 seats.

The centrist coalition of President Emmanuel Macron, who cast the country into turmoil a month ago by calling the election, was in second place with 150 seats. Trailing it was the National Rally and its allies, which took 142 seats.

The results were compiled by The New York Times using data from the Interior Ministry, and they confirmed earlier projections showing that no single party or bloc would win a majority.

The details of the outcome may still shift, but it is clear that, to a remarkable degree, a scramble by centrists and the left to form a “Republican front” to confront the National Rally in the second round of voting worked. Candidates across France dropped out of three-way races and called for unity against Ms. Le Pen’s party.