Thousands of left-wing demonstrators on Saturday took to the streets across France to protest against the nomination of the center-right Michel Barnier as prime minister and denounce President Emmanuel Macron's "power grab."
Police said that around 26,000 people demonstrated in Paris, while the left claimed a much higher turnout.
Smaller rallies took place in other cities across France including Nantes in the west, Nice and Marseille in the south and Strasbourg in the east.
Macron on Thursday appointed Barnier, a 73-year-old former foreign minister who acted as the European Union's Brexit negotiator, as prime minister, seeking to move forward after July snap elections in which his centrist alliance came in second.
Barnier said on Friday night that he was open to naming ministers of all political stripes, including "people from the left."
But a left-wing coalition, which emerged as France's largest force after the June-July elections, although without enough seats for an overall majority, has greeted Macron's appointment of Barnier with dismay.
The left-wing alliance wanted Lucie Castets, a 37-year-old economist, to become prime minister, but Macron quashed the idea, arguing that she would not survive a confidence vote in the hung parliament.
On Saturday, many demonstrators directed their anger at Macron, 46, and some called on him to resign.
"The Fifth Republic is collapsing," said protester Manon Bonijol. "Expressing one's vote will be useless as long as Macron is in power," added the 21-year-old.
Hard-left leader Jean-Luc Melenchon, whose France Unbowed party (LFI) and allies belong to the left-wing bloc, has charged that the election was "stolen from the French," and called on French people to take to the streets.
On Saturday, he urged supporters to prepare for battle.
"There will be no pause," he vowed.
"Democracy isn't just the art of accepting that you've won, it's also the humility of accepting that you've lost," Melenchon said at the protest.
Project manager Alexandra Germain, 44, accused Macron of riding roughshod over the wishes of voters.
"Demonstrating is my only way of saying that I don't agree, even if I am well aware that it is useless," said Germain.
Abel Couaillier, a 20-year-old student, said he was stunned by the appointment of Barnier whom he called an "old elephant."
"I am still young, I want to believe that we can change things," added Couaillier.
Leading LFI figure Mathilde Panot claimed on X that 160,000 demonstrators protested in Paris and 300,000 people across France.
Five people were detained in Paris, police said.
Marine Le Pen, who leads far-right National Rally (RN) lawmakers in parliament, has said her party would not be part of the new cabinet, and would wait for Barnier's first policy speech in front of parliament to decide whether or not to back him.
On Saturday, National Rally party head Jordan Bardella, who had hoped to be France's next prime minister, indicated that the far-right would be watching Barnier's every move.
Barnier immediately shot back, saying he had a responsibility toward all French people, not the far-right.
"I am under the surveillance of all French people," he said on the sidelines of a visit to the Necker children's hospital in Paris.
Barnier will be in charge of the budget, security, immigration and healthcare and will have to take the interests of the National Rally, the single largest party in a fragmented legislature, into account to avoid a motion of no confidence in parliament.
Barnier — who is likely to have only minority support in the Assembly — will face the urgent task of presenting the 2025 budget by early October.
