One poll shows any of 4 top candidate could reach runoff; second poll shows bigger gap, with far-left candidate Jean-Luc Melenchon lagging.

France’s presidential race looked tighter than it has all year on Friday, nine days before voting starts, as one poll put all four main candidates within touching distance of the two-person run-off round.

The Ipsos-Sopra Sterna poll for daily Le Monde showed centrist Emmanuel Macron and far-right leader Marine Le Pen tied on 22% each in the April 23, 2017 first round, with the far-left’s Jean-Luc Melenchon and conservative Francois Fillon at 20% and 19% respectively.

That 3% gap among the top four was within the poll’s margin of error, suggesting the election is wide open.

Were he to qualify for the second round on May 7, Mr. Macron is still seen winning whoever his opponent is, but the most striking trend of the past days has been Mr. Melenchon’s sharp rise in first round voting intentions since performing well in two TV debates in late March and early April.

A second poll published on Friday showed a bigger, 6% gap separating the four main players in a first-round field of 11 candidates. The daily survey by Opinionway had Mr. Macron as leader at 23% and Mr. Melenchon the laggard at 17%.

Mr. Melenchon’s progress is, however, worrying investors in view of his hostility to the European Union and plans to repeal pro-business labour reforms. Opinion polls show that, should he reach the second round, he could win against Mr. Fillon or Ms. Le Pen.

Polls have consistently shown that Ms. Le Pen, who is also hostile to the E.U. and wants to dump the euro, would not win the presidency whoever she faced in the run-off.

French judges investigating her alleged misuse of E.U. funds to pay for party assistants have asked for her parliamentary immunity to be lifted, though her legal woes have not been as harmful to her in the polls as the allegations of nepotism that have plagued Mr. Fillon’s campaign.

The Le Monde poll was conducted on April 12 and 13 among 1,509 people.