Pressure mounted Saturday on France's newly reappointed premier Sebastien Lecornu to get an austerity budget approved, as more parties threatened to topple a man whose first term lasted a mere 27 days.

President Emmanuel Macron reinstated Lecornu late on Friday, just four days after Lecornu's resignation and the collapse of his just-announced government.

The reappointment provoked outrage across the political spectrum and pledges to vote it down at the first chance.

In order to create a longer-lasting government, Lecornu pledged on Saturday to work with all the mainstream political movements and that he would select cabinet members who are not "imprisoned by the parties."

His reappointment comes as France faces political deadlock and a parliamentary impasse over a cost-cutting budget against a backdrop of climbing public debt.

Lecornu, 39, must form a cabinet to present a 2026 draft budget on Monday.

Outgoing Interior Minister Bruno Retailleau told members of his right-wing Republicans (LR) party that they should "not take part" in Lecornu's next government, though he did not call to vote it out of office and other members of the party expressed willingness to participate.

Meanwhile the leftist Socialists, a swing group in parliament, said they had "no deal" with Lecornu and would oust his government if he did not agree to suspend a 2023 pensions reform that increased retirement age from 62 to 64.

Lecornu said on Saturday during a visit to a police station near Paris that "all debates are possible" over the pension reforms, and that his "only ambition is to get out of this situation that is painful for everyone".

But far-right National Rally party leader Jordan Bardella -- whose party has never been considered to play any role in a coalition government -- called Lecornu's reappointment a "bad joke" and said he would immediately seek to vote out the new cabinet.

France has been mired in political deadlock ever since Macron gambled last year on snap polls that he hoped would consolidate power -- but ended instead in a hung parliament and more seats for the far right.

The country faces EU pressure to curb its deficit and debt, and it was the fight over cost-cutting measures that toppled Lecornu's two predecessors.

Lecornu has pledged to do "everything possible" to give France a budget by the end of the year, saying restoring the public finances was "a priority" for the future.

Time is running out however to give parliament the constitutionally required 70 days to examine the budget before year's end.

Macron, facing the worst domestic crisis since the 2017 start of his presidency, has yet to address the public since Lecornu's first government fell. (AFP)