“Past presidential elections have shown that two candidates can’t coexist on the left without causing trouble for each other,” said Erwan Lestrohan, research director at French polling institute Odoxa.

The two men could hardly be more different. Mélenchon is a 74-year-old hardliner who has run for president three times, nearly making the runoff in 2022 with a campaign calling for hiking the minimum wage, lowering the retirement age to 60 and pulling out of NATO.

Glucksmann, 46, is an MEP and staunch supporter of bolstering Europe’s military power. He is also open to billions of euros worth of spending cuts to bring France’s messy public finances into line and believes the country’s contentious pension system should be rebuilt.

Given those ideological fault lines, the tone of the contest has unsurprisingly descended into mudslinging. On his preferred communication outlet — his blog — Mélenchon has described Glucksmann as a “fanatic warmonger” and “the darling child of media vacuity.”

Punching back on social media and in interviews, Glucksmann has called Mélenchon “a phony patriot who prefers the Kremlin’s spin” and has framed their showdown as a struggle for “a vision of democracy,” accusing the leader of the hard-left France Unbowed party of rose-tinted views of authoritarian regimes in Moscow and Beijing.

Peril in the polls

Over recent weeks, poll after poll has suggested the far right could well have to face a leftist in a run-off in the spring of 2027.

“There’s a solid prospect of having a left-wing candidate make the second round,” Lestrohan said.