Still just 39, Lecornu has been one of the few faces of continuity in the French cabinet at a time of multiple changes of government.

The ultimate Macron loyalist, Lecornu's survival is a measure of the importance of his job three-and-a-half years into Russia's invasion of Ukraine and the trust accorded to him by Macron.

He was reportedly on the brink of being named premier in December 2024. But Francois Bayrou, 74, almost twice Lecornu's age persuaded Macron that he was the best person for the job.

Lecornu has worked staunchly to keep up assistance for Ukraine, while carefully remaining in the shadows with infrequent media appearances.

One of his key assets for Macron is that he is not what is known in France as "presidentiable", namely someone who harbours ambitions of winning the Elysee Palace for themselves.

Lecornu is "a loyal soldier who doesn't have too much charisma or presidential potential," one ministerial adviser told AFP on condition of anonymity.

- Life in politics -

A career politician, Lecornu started out as a parliamentary assistant aged just 19. He has held ministerial posts ever since Macron came to power in 2017 and was promoted to defence minister in May 2022.

Interested in politics from an early age, Lecornu's career set records for hitting milestones at an early age, initially with the conservative UMP party of former president Nicolas Sarkozy.

He served as an MP's assistant from 19 and became France's youngest-ever ministerial adviser in 2008, joining Bruno Le Maire -- later Macron's long-serving finance minister -- on the Europe brief.

In 2015, he was the youngest-ever president of a French department, Eure in Normandy, after serving as mayor of his hometown Vernon.

A graduate in public law rather than the elite administration or business institutions that traditionally shape top French leaders, Lecornu has made sure to keep up his local roots.

But he reached ministerial rank at 31, covering portfolios including the environment and overseas territories before landing at defence.

He is close to Macron's longtime interior minister and now Justice Minister Gerald Darmanin, a fellow transplant to the centrist camp from the traditional right

Lecornu has the advantage of "looking more serious than his age" in a French political scene still dominated by older men, one MP aligned with Macron's supporters told AFP.

He notched up points with Macron by helping organise the Great Debates the president held with local elected officials to defuse the "yellow vests" cost-of-living protests of 2018-19.