What to Know About France’s Snap Parliamentary Elections

President Emmanuel Macron threw French politics into disarray on Sunday when he unexpectedly called for snap elections.

The surprise move came after his party was battered by the far right in European Parliament elections. Mr. Macron dissolved the lower house of France’s Parliament and said the first round of legislative elections would be held on June 30.

France now finds itself in unpredictable territory, with the future of Mr. Macron’s second term potentially at stake. With less than a month to go before the poll, parties are now scrambling to field candidates, hone their messaging and, in some cases, forge alliances.

Here is what you need to know about the snap election.

What happened?

France’s far-right, anti-immigrant National Rally party, led by Marine Le Pen and her wildly popular protégé, Jordan Bardella, surged to first place in elections for the European Parliament on Sunday with about 31.4 percent of the vote. Mr. Macron’s centrist Renaissance party came in a distant second, with about 14.6 percent.

Mr. Macron acknowledged the crushing defeat in a televised broadcast to the nation that night.

“France needs a clear majority to move forward with serenity and harmony,” Mr. Macron said, explaining why he had decided to call for legislative elections.

That involved taking the extremely rare move of dissolving the 577-seat National Assembly, a presidential prerogative in France. Mr. Macron is the first president to do so since 1997.

Why did he do it?

When Mr. Macron was elected to a second term in 2022, his party failed to win an outright majority. The centrist coalition he formed has since governed with a slim majority — but struggled to pass certain bills without support from the opposition.

Mr. Macron was under no obligation to dissolve Parliament, even if the European vote left him a reduced figure with three years left in his presidential term. Analysts are still parsing through his motivations, although many suspect that he believed a dissolution had become inevitable — conservative lawmakers were threatening to topple his government in the autumn. Jolting the country with a sudden election could also be a way for Mr. Macron to prevent his opposition from organizing — and to present voters with a stark choice between him or the far right.

The move is seen as a gamble: If the National Rally repeats its performance in national elections, France could become nearly ungovernable, with Mr. Macron confronting a Parliament hostile to everything he believes in.

Ms. Le Pen welcomed the announcement of elections and expressed confidence that her party could muster a majority. “We are ready to turn the country around,” she told cheering supporters in Paris on Sunday evening.

What’s at stake?

The presidency is France’s most powerful political office, with broad abilities to govern by decree. But the approval of Parliament, and especially the National Assembly, is required on most big domestic policy changes and key pieces of legislation, like spending bills or amendments to the Constitution.

Unlike the Senate, France’s other house of Parliament, the National Assembly is elected directly by the people and can topple a French cabinet with a no-confidence vote. It also has more leeway to legislate and challenge the executive, and typically gets the final word if the two houses disagree on a bill.

Mr. Macron’s party and its centrist allies currently hold 250 seats in the National Assembly, short of the 289 required for an absolute majority. The National Rally party holds 88 seats, while the mainstream conservative Republicans have 61. A tenuous alliance of far-left, Socialist and Green lawmakers holds 149 seats. The remainder are held by smaller groups or lawmakers not affiliated with any party.

How will the vote work?

The elections for the 577 seats in the National Assembly will be held in two rounds — the first on June 30 and the second on July 7.

France’s 577 electoral districts — one for each seat — cover the mainland, overseas departments and territories, as well as French citizens living abroad. Unlike many of its European neighbors, France awards seats to candidates who get the most ballots in each district, not based on a proportion of the total vote across the country.

That means there will be 577 separate races, with local dynamics and quirks — unlike the European parliamentary elections where each party fielded a single, nationwide list of candidates.

Any number of candidates can compete in the first round in each district, but there are specific thresholds to reach the second round. While in most cases the runoff will feature the top two vote-getters, on rare occasions it might feature three or even four candidates. Whoever wins the most votes in that runoff wins the race. (Under some conditions, a candidate who gets more than 50 percent of the vote in the first round wins outright.)

What happens next?

Because the elections have just been announced, there is no reliable opinion polling yet.

Despite its triumph in the European elections, it is unclear whether the National Rally can capture a significantly larger number of seats in the lower house of the French Parliament.

“It’s hard to project the results of the European elections onto the legislative ones,” said Luc Rouban, a senior research fellow at the Center for Political Research at Sciences Po in Paris. “It’s not sure that the National Rally will have the same success.”

With little time to campaign, parties on the left are scrambling to unite like they did in 2022 by avoiding competing candidacies in each district. But unity on the French left can be elusive, and it is unclear whether the parties will be able to strike such a deal.

If Mr. Macron is unable to muster a strong parliamentary majority, he could find himself in a rare “cohabitation” scenario — where the presidency and the National Assembly are on opposing political sides.

In that scenario, Mr. Macron would be compelled to choose a prime minister of a different political party — which could potentially block much of his domestic agenda. Foreign policy, which is a presidential prerogative, would theoretically remain mostly untouched.