For many, France feels like a very different place on Monday.

The results from the first round of legislative elections, held on Sunday, revealed a country deeply fractured, with a surging far right winning a record number of votes and the near collapse of President Emmanuel Macron’s centrist party.

“The far right at power’s door,” the cover of Le Parisien, a daily newspaper, pronounced the morning after the first half of the snap election called by Mr. Macron.

“Twelve million of our fellow citizens have voted for a far right party that is clearly racist and anti-Republican,” the left-leaning Libération newspaper declared in an editorial, referring to Marine Le Pen’s National Rally party. “The head of the state threw France under the bus, the bus continued without slowing down, and now it’s parked in front of the gates of Matignon” — the prime minister’s office.

If the National Rally takes an absolute majority in the runoff on Sunday, Mr. Macron will be forced to appoint a prime minister from its ranks, who will in turn form a cabinet.

There was a sense of whiplash and disbelief at the political nosedive of Mr. Macron’s party, which with its allies has had the most seats, but not an absolute majority, in the National Assembly. That centrist coalition finished a distant third in the first round of the two-round electoral race. Only two of his candidates — and not one of his ministers who were running for a seat — got enough votes to be re-elected without a runoff for their positions, compared with 37 members of the far-right National Rally, and 32 of the left-wing coalition of parties called the New Popular Front, which came in second.

The results of the first round of voting do not typically provide a reliable projection of the number of parliamentary seats each party will secure. But the National Rally now looks very likely to be the largest force in the powerful National Assembly. The question is whether it will get enough seats to command an absolute majority.

If that does not happen, the National Assembly will most likely be ungovernable, with Mr. Macron’s centrist party and its allies squeezed between the right and the left and with greatly diminished power.

“End of an era,” declared the front page of Les Echos, the main business daily.

“When historians look back on the dissolution, they will have only one word: disaster!” stated an editorial in the conservative newspaper Le Figaro.

“Emmanuel Macron had everything, or almost everything,” it continued. “He lost everything.”

On the ground, the reaction to the vote reflected the country’s divisions. In the north, considered a stronghold of the far-right National Rally, there was jubilation.

“I’m going to party all night long,” Manuel Queco, 42, a contractor, said in a local hall in the town of Hénin-Beaumont, where Ms. Le Pen was receiving one round of congratulations after another on Sunday evening, after she was elected outright in her own race. As the crowd of National Rally supporters burst into a round of the national anthem, Mr. Queco raised his glass of Champagne. “I’ve been waiting for them to win since I was 18 years old.”

In Paris, the results of the first round revealed an electoral map that had blocked out the National Rally almost entirely, but was divided between the New Popular Front and the president’s party. Yet, the predominant feeling in the Place de la République, where thousands of left-wing supporters gathered Sunday night, was one of sorrow and commiseration.

“I never thought I would see this in my life — the far right leading the country,” said Camille Hemard, 50, a professor of Latin, Greek and French at an advanced preparatory college. She had brought along her 16-year-old daughter to seek solace in the crowd that danced and chanted, “Everyone hates the fascists.”

She added, “I had hoped my children would not know this.”

From the radio, television sets and news websites, pollsters reminded people that not everything was decided. Only 76 of the country’s 577 legislative seats were won outright. A battle would ensue for the remaining 501 this week, until the definitive vote on Sunday. The question many were asking was how many candidates would drop out of three-way races in a strategic move to block the far right from winning.

Official results published by the Interior Ministry showed that the National Rally and its allies won about 33 percent of the vote. Mr. Macron’s centrist Renaissance party and its allies took about 20 percent, and the New Popular Front won about 28 percent of the vote.

Ségolène Le Stradic contributed reporting from Hénin-Beaumont, France.