President Emmanuel Macron is on Saturday to be inaugurated for a new term after his election victory over the far right made him the first French head of state for 20 years to win a second mandate.

The event, starting at 0900 GMT at the Elysee Palace, kicks off a series of key steps as Macron begins a new five-year term filled with international and domestic challenges.

Macron faces a daunting agenda of implementing the reforms he vowed when he came to power as France's youngest-ever president in 2017, as well as dealing with the Russian assault against Ukraine.

The head of the Constitutional Council, Laurent Fabius, will read a statement confirming Macron's victory in the second round of presidential polls on April 24 with a score of 58.55 percent against far-right rival Marine Le Pen.

Macron will then deliver a keynote speech which according to an Elysee official "will not be a general political speech but is part of the history of the country and will look at the future".

In a tradition dating back to the Middle Ages, 21 cannon shots will then be fired from the Invalides military memorial complex to celebrate the inauguration.

With no drive down the Avenue des Champs-Elysees or long red carpet, the ceremony will resemble the re-inaugurations of Francois Mitterrand in 1988 and Jacques Chirac in 2002, the last French president to win a second term.

PM quandary

Despite the ceremony, Macron's second term will only start officially when the first one expires at midnight on May 13.

It comes at a time of political flux in the wake of Macron's election victory, as France gears up for legislative polls that swiftly follow in June.

Macron is expected to name a new premier in place of incumbent Jean Castex to lead a revamped government into the elections, but not until his second term officially kicks off.

He has mooted naming a female politician with a focus on social responsibility -- although reports have indicated that overtures to leftist figures, such as former official Veronique Bedague and Socialist parliamentary group chief Valerie Rabault, have been rebuffed.

"If there was a obvious solution for the Matignon (the residence of the prime minister) it would have been announced long ago," a source close to Macron, who asked not to be named, told AFP.

Meanwhile, the Socialist Party along with the Greens and Communists, is forming an unprecedented alliance for the parliamentary elections with the hard left France Unbowed (LFI) party of Jean-Luc Melenchon.

He was by far the best performing left-wing candidate in the first round of presidential elections and is spearheading efforts to form a broad bloc and mount a convincing challenge to Macron.

Pro-Macron factions have regrouped under the banner of Ensemble (Together) while his own Republic on the Move party, which has struggled to create a grass-roots base, is renaming itself Renaissance.

Huge challenges await the 44-year old president.

He is set to keep playing a leading role in efforts to stop Russia's war against Ukraine, while he carries an immense burden of expectation as a leader on the European stage with Germany still finding its footing in the post-Angela Merkel era.

On the domestic front, he must deal with the crisis over the rising cost of living and also brace for possible protests when he finally tackles his cherished pension reform, raising France's retirement age.