PARIS — French voters are going to the polls on Sunday to cast ballots in crucial parliamentary elections that will determine the fate of President Emmanuel Macron’s domestic agenda during his second term, after a bitter campaign that pitted his party and its centrist allies against a reinvigorated left-wing coalition.
Voters across France are choosing their representatives in the second and final round of voting for the 577-seat National Assembly, the lower and more powerful house of Parliament, which has a pre-eminent role in drafting and passing legislation.
Mr. Macron’s party and its allies are expected to win overall, but perhaps without securing the broad majority that they have enjoyed since 2017. If his forces fail to clinch enough seats, Mr. Macron could find it harder to get bills passed and to enact some of his more contentious projects, like his plans to raise the legal age of retirement to 65 from 62.
“We are used to seeing France’s system as centered on the presidency” because it is the most powerful political office in the country, said Olivier Rozenberg, an associate professor at Sciences Po in Paris. But “these legislative elections remind us that our political system is also a parliamentary one at heart.”
In the first round of the elections, last week, a pro-Macron centrist alliance known as Ensemble finished neck and neck with NUPES, the Nouvelle Union Populaire Écologique et Sociale, the left-wing alliance led by Jean-Luc Mélenchon, a veteran leftist politician.
Both forces got roughly 25 percent of the vote nationwide amid general voter apathy, despite growing concerns over inflation. Only 47.5 percent of French voters went to the polls last week, the lowest turnout in the first round of a legislative election since 1958.
France’s electoral system awards seats to the candidate who wins the most ballots in each district, rather than a proportion of the total vote across the country. Pollsters say it is hard to accurately predict the second-round results because each race is different.
While they expect Mr. Macron to get a majority, the number of seats they project for his alliance has varied wildly since the first round — anywhere from 250 to 310 seats, versus 150 to 220 for NUPES, which includes Mr. Mélenchon’s party, France Unbowed, as well as the Socialists, Greens and Communists.
If pro-Macron forces get an absolute majority — more than 289 seats — the president will be able to get legislation passed with relative ease. If they get more seats than other groups, but not more than half of the total — what the French call a relative majority — Mr. Macron could be forced to reach out to opposing lawmakers, most probably on the right, for support on certain bills.
And if NUPES emerges with the most seats, it could force Mr. Macron to appoint Mr. Mélenchon prime minister, ushering in a new era of forced cohabitation between a president and a cabinet of opposite political persuasions, working at cross-purposes. This would be a stunning shift for Mr. Macron’s second term, but pollsters say it is unlikely.
NUPES has promised voters they could metaphorically “elect” Mr. Mélenchon prime minister, and he has used his oratory to galvanize left-wing voters after a disastrous presidential election in which the left was divided and largely sidelined.
Mr. Mélenchon has vowed that his coalition would bring the legal age of retirement to 60, raise the monthly minimum wage to $1,580, overhaul the Constitution to reduce presidential powers and phase out nuclear power.
Sarah Benkirane, 30, an executive assistant who had just cast a ballot for NUPES in Amiens, a town in northern France, said on Sunday she was the only person among her friends and family who had voted.
“But I’m aware that my vote can change things,” Ms. Benkirane said, adding that she had been disappointed by the left’s lack of unity for the presidential elections. “We shouldn’t miss a new opportunity.”
Mr. Macron appeared disengaged from the election and more preoccupied with France’s diplomatic efforts to support Ukraine in its war against Russia. Speaking on an airport tarmac before a trip to Eastern Europe that took him to Kyiv, the Ukrainian capital, this week, he had urged voters to give him a “solid majority” for the “superior interest of the nation.”
Eve Minart, 42, a stay-at-home mother in Amiens, said she was not particularly enamored with the Ensemble candidate in her district — Mr. Macron’s former minister for the environment — but had still voted for her because she did not want a left-wing majority.
“With Covid, the war in Ukraine, we need stability,” Ms. Minart said. “The complete opposite of what Mélenchon would do as prime minister.”
Adèle Cordonnier contributed reporting from Amiens, France.