Five days before the first round of the presidential vote in France, four candidates are so close in polls they could all qualify for the runoff in the country's most unpredictable election in decades.

The centrist Emmanuel Macron and the extreme-right Marine Le Pen are neck-and-neck ahead of Sunday's (23 April) election, according to the Elabe pollster in L'Express, a magazine.

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The survey gave Macron 24 percent of the vote and Le Pen 23. The same poll showed the conservative Francois Fillon and the far-left Jean-Luc Melenchon winning 19.5 and 18 percent, respectively.

A separate poll in Opinionway, a daily, said Macron was tied with Le Pen on 22 percent, and that Fillon was snapping at their heels on 21 percent followed by Melenchon on 18 percent.

All candidates campaigned over the Easter weekend to convince undecided Frenchmen - one fourth of the electorate.

Le Pen, who has worked to erase the image of racism and anti-Semitism that defined her party for years, returned to her base and stressed anti-migrant messages in her rally on Monday.

Speaking to 5,000 supporters who had gathered in a concert hall in Paris, she promised a "moratorium on illegal immigration to put an end to this delirium, this uncontrolled situation, which drags us to the bottom."

Le Pen was long the favourite in the race, but has lost four percentage points since February according to a count by the Huffington Post.

Her return to hardline immigration messages could scare off more moderate voters in what amounts to a political gamble.

Macron, campaigning in a sports hall in Paris, opted for a message of unity and said he wanted to take "the best of the left, the best of the right and the best of the centre".

The centrist candidate, who has been mocked for his refusal to chose sides, poked fun at himself and commented on his frequent use of the expression "at the same time".

"They say it's a linguistic tic that would mean that I am not clear, that I do not know how to decide, that I would be blurry," he told the 20,000 supporters who had gathered to see him, before reclaiming the expression as his catchpharse.

"Yes, I choose liberty and equality, growth and solidarity, the enterprise and the employees," he said.

Fillon campaigned in Nice, in southern France, where he highlited the fight against terrorism and Islamism as his main theme.

"I want to address myself to all the women who are hidden, mistreated and forced to dress differently in the name of religion. I tell them I will fight on their side to defend their fundamental rights," he said, before accusing the left of aiding the rise of Islamism in the country.

Fillon will, this week, campaign in northern France, where the far-right has been scoring gains.

He has also allied himself with the conservative Catholic voters of the "Common sense" movement, which mobilised large anti-gay demonstrations some years ago.

The unruly barge

Melenchon, a far-left firebrand who is opposed to both Europe and Nato, and whose ratings have been buoyed by his performance in TV debates where he came across as the most humorous candidate.

He has kept campaigning in the same style at the weekend, saying that jokes were the best remedy against national gloominess.

On Monday, he campaigned from a barge, dubbed the "unruly barge", which crossed Paris.

"Here you are listening to a guy on a boat on Easter Monday. There's something in the air!", he told his cheering supporters, while adding that he could lose the election by a "handful of votes".

"It's not true that your only choice is between being hash dealers and working for Uber," he told Parisians strolling around the canals.

He also amplified his recent attacks on mainstream media, whom he accused of painting a black image of his candidacy.

Les Echos, the financial paper of France, recently called him a "risk".

"Eh oui, I am very dangerous," the left-wing presidential candidate said in English and French, prompting more laughter.