Four candidates are still in contention to make it to a second round two weeks after Sunday's ballot. The first round could bring last minute surprises given that the predicted abstention rate and the degree of indecision are high.
France's tumultuous election campaign, marked by surprising outcomes in the two main party primaries, the relegation of early frontrunners for the presidency, and the rise of Macron's independent political movement, has become increasingly tense as the gap between candidates shrinks.
The stakes for investors are high, with two anti-EU, anti euro candidates among the four.
Macron and far-right leader Marine Le Pen have lost steam in the run-up to Sunday's vote, but are still expected to qualify for the May 7 run-off, with the centrist winning that second round, according to a Cevipof poll of 11,601 people for Le Monde newspaper.
The poll is one of the most comprehensive surveys among a mass of competing ones released on a daily basis.
Le Pen, who has been pressing home her core message on stopping immigration in the past week, dropped by 2.5 percentage points to 22.5 percent of voting intentions compared with early April, and Macron fell 2 percentage points to 23 percent in the first round, Cevipof said.
Far-left firebrand Jean-Luc Melenchon, who has surged in recent weeks, was on 19 percent, the poll showed, while conservative leader Francois Fillon, recovering from a nepotism scandal, was on 19.5 percent.
Abstention, a key factor adding to uncertainty over the outcome of the first round, was seen coming at 28 percent, Cevipof said.
All of the Cevipof findings were broadly in line with recent polling trends that show the race very tight.
The abstention rate was in line with a record level in the 2002 election, where the then National Front leader - Le Pen's father Jean-Marie Le Pen - made it to the run-off before he was beaten by conservative Jacques Chirac.
Security concerns have come to the fore after two men were arrested in Marseille on Tuesday, suspected of planning an imminent attack aimed at the presidential campaign.
The Paris prosecutor said on Tuesday that a video linked to the two Frenchmen and intercepted in early April had featured a machine gun placed on a table as well as a newspaper which had one of the presidential candidates on the front page.
A source close to the investigation said on Wednesday that the candidate featured on the newspaper cutting was Fillon.
France's internal intelligence agency had warned the main candidates of a threat, campaign officials said.
Le Pen said in a radio interview on Wednesday that her team had also been warned of a threat and that her security entourage had been given photos of the suspects.
"We were warned of the risks, as were the other presidential candidates, who were given pictures of these individuals as of Thursday night so that our respective security services could be more prudent," Le Pen told France Bleu Gard Lozere.