France's newly reappointed prime minister, Sebastien Lecornu, was racing against time on the weekend to form a Cabinet and build a consensus ahead of a crucial draft budget vote on Monday.

President Emmanuel Macron reappointed Lecornu on Friday, four days after he resigned amid division over the country's pension reforms and after only 26 days on the job.

But after Macron urged Lecornu to try again to build a consensus, the conservative Les Republicains party signaled on Saturday its lawmakers likely will not support the government because "the trust and conditions are not in place", Le Monde newspaper reported, quoting the liberal-conservative party's governing body.

The Reuters news agency said France's succession of prime ministers and their inability to build a consensus amounts to the nation's biggest political crisis for decades.

Michel Barnier, himself a recent prime minister who failed to paper over the cracks between France's left-wing and right-wing in the nation's finely balanced Parliament, wrote on X on Saturday that his Les Republicains party should only consider supporting the government if it does not abandon Macron's pension reforms, which include a universal retirement age of 64.

"Our support must remain demanding and faithful to the battles we are waging for the French," Barnier wrote.

He said his party should also only support the government if it also makes provisions to reduce the deficit, boost security, and enhance the competitiveness of businesses.

The centrist Union of Democrats and Independents said it will support Lecornu's budget but will not participate in his Cabinet.

And the center-right Horizons party has also said it will not participate in the Cabinet, if the government attempts to delay its pension reforms.

Lecornu faces the difficult job of keeping those centrist and rightwing parties minded to support his budget onside while also trying to win some support from the left-wing parties strongly opposed to the pension reforms.

Socialist Party leader Olivier Faure has already described Lecornu's reappointment as part of an "endless day" and told La Tribune Dimanche newspaper he plans to vote to bring down the government as soon as possible if it does not abandon the pension reforms.

Reuters quoted Lecornu as saying he is open to being flexible about the pension reforms, saying "all debates are possible as long as they are realistic".

"I am setting myself a fairly clear mission, and then either the political forces will help me and we will work together to achieve it, or they will not," he said.

But he told La Tribune Dimanche on Sunday he will not be in the job for long if the illusive consensus continues to elude him.

"If the conditions were no longer met again, I'd leave," he said. "I'm not going to just go along with whatever."