Le Pen, 48, has spent years trying to grow support for the FN by campaigning on bread-and-butter issues, but in the final days of the race she has returned to its stock themes of immigration and national identity. In five years, when not a thing has changed in France, they will start the whole wearisome rigamarole again.

French President Francois Hollande on Wednesday vowed to mobilize "all appropriate means" to ensure security during the two-round presidential election set to start on Sunday, his office said in a statement. Macron, who visit Algeria two months ago, also recognised that the occupation was a "war against humanity".

After Sunday's vote, the two leading candidates will progress to the second and final round of voting on Sunday April 7.

French presidential election candidate for the En Marche! movement Emmanuel Macron reacts during his visit at the KRYS group's headquarters in Bazainville, near Paris Tuesday April 18, 2017.

French presidential candidate Emmanuel Macron spoke with former US president Barack Obama on the phone on Thursday, in an apparent sign of support just three days before the first round of an uncertain presidential election. The Bloomberg Composite of first-round polls showed Macron nearly two points ahead, on 24.2 percent.

However, they also show Le Pen losing in the run-off whoever she faces, as many voters would rally behind her opponent simply to keep the far-right out of the presidency. If Le Pen wins, France might leave the European Union, following the United Kingdom, and triggering a level of uncertainty that could well lead to the downfall of the single market.

Four candidates are still in contention to make it to a second round two weeks after Sunday's ballot.

Fillon's margin of victory over Le Pen is seen as the smallest, so investors may find this second-round scenario more chilling than the above pairing.

Support for far-left candidate Melenchon and his far-left France insoumise alliance - which can be translated as "Unbowed France" - was at 19 percent, according to the Cevipof poll. In any runoff between the two on May 7.

Their resilience has been among the election's many surprises: Fillon because his campaign seemed mortally wounded by revelations that his wife and children benefited from cushy, and allegedly illegal, publicly funded jobs and Macron because his startup electoral campaign caught fire despite hostility from the political establishment.

The outcome will be watched closely by France's allies given its role as a nuclear-armed permanent veto-wielding member of the U.N. Security Council and its military and diplomatic clout in the Middle East and West Africa. However, the big question ahead of the vote may be if a recent surge in the vote share of Melenchon has been truly captured, he said. "There's North Korea, Turkey, the thwarted (terror) attack - all things that could tip the vote".

Crowds danced on a Paris plaza as Socialist presidential candidate Benoit Hamon held what is seen as a last-chance rally and concert.

French police say thieves stole a computer and a police armband from a auto used by aides to presidential candidate Francois Fillon. Those subjects won her her core backing, and she hopes it can give her boost with about 30 percent of voters still undecided. "I'll hesitate to the end".