French President Emmanuel Macron has said he will not agree to a government led by the left-wing New Popular Front alliance (NFP), which won the most seats in last month's legislative election.
Mr Macron said France needed institutional stability and the left could not win a confidence vote in parliament.
The NFP, which put forward the relatively unknown civil servant Lucie Castets as its candidate for prime minister, in response called for street protests and Mr Macron's impeachment.
Mr Macron - whose centrists were beaten to second place in July - said he would start new consultations with party leaders on Tuesday, and urged the left to cooperate with other political forces.
No one group was able to win a majority in the elections, with the NFP gaining more than 190 seats, Mr Macron's centrist Ensemble alliance 160 and the far-right National Rally (RN) 140.
A caretaker government has since led France, including during the Paris Olympics, to the anger of the NFP.
Mr Macron has been holding talks on a new government since the election, and said he would continue to do so.
"My responsibility is that the country is not blocked nor weakened," his statement on Monday said.
"The Socialist Party, the Greens and the Communists have not yet proposed ways to cooperate with other political forces. It is now up to them to do so," he added.
But he noticeably failed to mention one of the main elements that makes up the NFP, the hard-left France Unbowed movement (LFI).
The LFI reacted angrily to the president's words, with national coordinator Manuel Bompard describing them as an "unacceptable anti-democratic coup".
Communist leader Fabien Roussel told BFM TV Mr Macron was going to trigger a "serious crisis in our country", while Green leader Marine Tondelier said on X that three-quarters of the French people wanted a "political break with Macronism".
The leftist coalition has previously refused to take part in any future consultations unless the candidacy of Ms Castets for prime minister is discussed.
However, the 37-year-old economist is unelected and seen as an unlikely presidential pick.
Both Ensemble and RN have vowed to vote down candidates from the NFP.
After meeting Mr Macron for talks on Monday, RN leaders Marine le Pen and Jordan Bardella described the NFP as a "danger" for France.
Among other names discussed in political circles are former Socialist interior minister Bernard Cazeneuve and Xavier Bertrand, who is a regional leader from the centre-right Republicans.
