Hours after he fell short of making it into the final phase of France’s presidential election, the veteran leftist Jean-Luc Mélenchon had a message for his supporters: they should not give “a single vote” to far-right candidate Marine Le Pen in the second round in two weeks. Now the identity of France’s next president might depend on whether they listen.

Mélenchon’s strong showing in Sunday’s first round, when he won 22 per cent of the vote, has put him and his voters in the position of kingmakers as incumbent president Emmanuel Macron battles Le Pen during the final days of campaigning. Macron, in particular, needs as many Mélenchon supporters as possible to back him to win on April 24.

Mélenchon’s message of rejection for Le Pen would seem to favour the president. But Mélenchon stopped short of prompting supporters to vote Macron and his party is due to consult members on whether to do so.  The president faces a fight to win over far-left supporters who are far less inclined to help him than in 2017, when he coasted to victory against Le Pen, and stop them from abstaining.