French President Emmanuel Macron has lost his parliamentary majority after election gains made by a newly formed left-wing alliance, Nupes, and the far right.
The result from Sunday's second-round poll could lead to political paralysis in the legislature or messy coalitions that will force the French president to reach out to new allies.
Mr Macron, 44, now also risks being distracted by domestic problems at a time when he has sought to play a prominent role in putting an end to Russia's invasion of Ukraine and become a key statesman in the EU.
His “Together” coalition will still be the biggest party in the next National Assembly. But with 245 seats, according to full interior ministry results announced in the early hours of Monday, it is well short of the 289 seats needed for a majority in the 577-member chamber.
“This situation constitutes a risk for our country, given the challenges that we have to confront,” Prime Minister Elisabeth Borne said. “We will work from tomorrow to build a working majority.”
The outcome severely tarnished Mr Macron's April presidential election victory when he defeated the far-right to become the first French president to win a second term in over two decades.
“It is a turning point for his image of invincibility,” said Bruno Cautres, a researcher at the Centre for Political Research of Sciences Po.
Daily newspaper Le Monde had a headline on its website that read: “Macron faces the risk of political paralysis,” while the Le Figaro said the results raised the spectre of a “stillborn new mandate”.
Nupes, led by hard-left figurehead Jean-Luc Melenchon, won 135 seats, according to an AFP count based on results published by the ministry.
The coalition, which was formed in May after the left splintered before April's presidential elections, brings together socialists, the hard left, communists and greens.
Mr Melenchon, 70, called Sunday's results “above all an electoral failure” for Mr Macron.
“The rout of the presidential party is total and there will be no majority [in parliament],” he told cheering supporters in Paris.
A prominent politician from Mr Melenchon's party, Alexis Corbiere, said the result meant Mr Macron's plan to raise the French retirement age to 65 had been “sunk”.
Far-right leader Marine Le Pen's National Rally party made huge gains and will send 89 MPs to parliament, making it the biggest right-wing force in the legislature, followed by the traditional right, The Republicans.
Ms Le Pen described her party's win as historic and said it would send, “by far”, its highest number of politicians to the next National Assembly.
Mr Macron had hoped to stamp his second term with an ambitious programme of tax cuts, welfare reform and the raising of the retirement age.