France's new prime minister will sit down with the leaders of the nation's many political parties in the coming days, in the hope of building a consensus around his budget.

Francois Bayrou, who President Emmanuel Macron appointed prime minister on Friday, told La Tribune Dimanche on Sunday that his charm offensive would begin on Monday, with Marine Le Pen, leader of the far-right National Rally, or RN.

"My first job is to be a builder and, failing that, a repairman," he said.

The Reuters news agency said Bayrou, who leads the liberal Democratic Movement, will meet party leaders in order, with Le Pen first because RN was the party that had the most lawmakers elected in the snap election Macron called in June.

While the election failed to deliver a majority for centrist Macron, it also came too soon for Le Pen, whose popularity was growing fast but who failed to win the outright majority she needed to govern.

Instead, the French parliament is now balanced to the point where no party can force its will on the others.

The New Popular Front leftist alliance of parties is the largest bloc, but it too is not large enough to outvote its opponents.

Bayrou, who is the fourth person this year to serve as prime minister and the sixth under Macron since he came to power in 2017, will try to win over enough party leaders to get his budget approved, a task that defeated his predecessor, Michel Barnier, who was ousted in a confidence vote on Dec 4.

The Moody's credit rating agency has already delivered a verdict on the likely outcome of his efforts, saying on Friday the new government will probably fail to sort out the country's deficit and its bloated spending on public services and downgrading France's economy, from Aa3 to Aa2.

Moody's concluded by saying it believes France's finances will be weaker during the coming three years than they were in October.

France 24, which described Bayrou as a political heavyweight who has "stood by" Macron throughout his presidency, said the new prime minister is facing a huge challenge.

But the new prime minister, who himself ran for president in 2002,2007, and 2012, has long been and touted as a possible prime minister and is respected by many, in spite of having been acquitted in February in a case involving his alleged fraudulent employment of parliamentary assistants and the judge saying at the time that he was giving Bayrou the "benefit of the doubt".

Bayrou told La Tribune Dimanche that, despite the magnitude of the task, he "will be a prime minister of full function and complementarity (to Macron)".

"You must never forget that you are passing through, even if it may last," he said.