Sunday was a good day for French President Emmanuel Macron. Just weeks after his remarkable win in the French presidential election, Macron's recently established political party took a huge lead in the first round of voting for the country's legislature, the National Assembly. The Republic on the Move party is projected to win 390 to 430 of the French Parliament’s 577 seats, according to an Ipsos-Sopra analysis.

But observers noticed an uncomfortable detail in the electoral figures: Turnout of registered voters was the lowest it has been in any parliamentary election under France's Fifth Republic.

It's certainly an unusual detail. Voter turnout in French elections is often remarkably high by American standards. Macron had billed himself as the leader of a popular centrist movement, but less half of registered French voters bothered to turn up.

Political opponents used the turnout to criticize the legitimacy of the French president. “I am particularly concerned about the fact that 1 French person out of 2 did not vote,” Valérie Pécresse, president of the ­center-right Republicans party in the Ile-de-France region, told Le Monde newspaper. “We weaken Parliament, which is a democratic counter-power. And we take the risk of a single party, a single thought, a single program.”

Marine Le Pen, leader of the far-right National Front party, voiced similar concerns. “This catastrophic abstention rate should raise the question of the voting rules, which keep millions of our compatriots away from the polling stations,” said Le Pen, according to the France 24 television network. Le Pen had faced off against Macron in the second round of France's presidential election and is a candidate for Parliament in the town of Hénin-Beaumont.

Some foreigners compared the limited turnout unfavorably with the British parliamentary elections that took place only a few days before. In that election, Jeremy Corbyn's leftist Labour Party gained 40 percent of the vote, with a turnout of 68.7 percent, but still won only the second-largest amount of seats in Parliament. In contrast, Macron's Republic on the Move was estimated to have received 32 percent of the vote with a turnout of 48.6 percent — but looks to dominate the National Assembly in a landslide.

Such comparisons are limited by the differences in electoral systems, however. Britain's is a parliamentary democracy (and one in the throes of a divisive political process to leave the European Union). France, however, has a semi-presidential system. And one reason for the lack of enthusiasm for the vote may have been simple fatigue. French voters had already gone to the poll twice in the past two months.

Given that the polls already showed a huge victory for Republic on the Move, many French voters may have wondered whether there was any point in casting ballots to choose their legislative representation. Additionally, in much of the country it was scorchingly hot Sunday.

Macron's likely dominance of the National Assembly will work in his favor, especially given the collapse in support for both traditional mainstream parties — the Republicans and the Socialists — as well as the far-right National Front. Initial polls suggested that supporters of Le Pen's National Front and the upstart leftist Jean-Luc Mélenchon were most likely to abstain from the vote — but if voter turnout doesn't improve in the second round, it will likely be used to criticize Macron's legitimacy.

The next round of voting will be held June 18.

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Macron’s party headed for commanding position in French election