Emmanuel Macron, the French President, warned of an "existential risk" to the European Union as he waded into the European election campaign ahead of a knife-edge vote between his centrist party and the far-right.
French presidents, as guardians of the Republic, are nominally supposed to remain above the fray in national elections but the unwritten rule is regularly flouted.
Macron had already lent his face to campaign posters, replacing that of the lacklustre head of his party's campaign, former Europe minister Nathalie Loiseau. He also met candidates on his La République en Marche! party's Renaissance list.
But he went further with a lengthy, joint interview published in regional French newspapers.
"I cannot be a spectator, but a participant in what is the most important European election since 1979, because the union is facing an existential risk," Macron said, adding that his rivals - chief among them Marine Le Pen, the leader of the far-right National Rally - had turned the election into a "referendum" for or against his two-year-old presidency.
Opinion polls have suggested that Macron's centrist list is running neck and neck with that of Le Pen, 50, who is seeking revenge following her heavy defeat to the 41-year-old in the French presidential run-off of 2017.
Macron's critics say that he has no business taking sides in the election while analysts have warned that doing so could set him up for a fall should his party fail to come first.
"He's acting like the head of a clan. It's not his role today," Jordan Bardella, the head of the National Rally list for the 2019 European Parliament election, said during a radio interview.
Macron countered: "The French president isn't the head of a party, but it's normal that he be involved in these fundamental choices."
Shortly before the interview's release, the French President had called for a "grand coalition of progressives" to fight "those who want to destroy Europe through nationalism", after meeting with António Costa, Portugal's Socialist Prime Minister.
In the interview, he said that Europeans were facing a critical choice on the future direction of Europe and on how to tackle migration and stand up as a continent to China and the US.
The release was marred by the decision of two local newspapers - La Voix du Nord and Le Télégramme - to boycott the interview.
The papers said they took issue with the Elysée's condition that the interview was submitted for prior approval before publication. They also said that if they interviewed Macron, they would have to do the same for all 33 other electoral lists.
Macron warned that low turnout was a major threat. Polls suggested it could be as low as 40 per cent.
"Deciding not to vote means deciding to give a voice to those who would destroy Europe," Macron said.