Opinion polls have shown far-right Marine Le Pen and centrist Emmanuel Macron qualifying on April 23 for a run-off election two weeks later in May. But the gap between them and conservative Francois Fillon and far-leftist Jean Melenchon has been narrowing.

A recent OpinionWay poll puts Macron and Le Pen both on 22 percent for the first round of the election, with Fillon on 21 percent and Melenchon up one point at 18 percent.

Two other polls had Macron just ahead of Le Pen in the first round and beating her comfortably in the second. An IFOP poll published on Tuesday indicated up to 30 percent of voters may abstain in the first round. 

The election will move into a run-off round on May 7, provided no candidate secures more than 50 percent of the vote on in round one on Sunday.

Macron calls for strong EU

Macron called for a "confident France" and defended his pro-EU position at his biggest rally of the campaign to date, attracting 20,000 people to the Bercy arena in Paris. 

"Of 11 candidates, 10 want to take us back to a fantasy vision of the past," he said. "I am for both a strong France and an ambitious Europe."

The former economy minister also reiterated his desire for a "solid and equal alliance" with Germany.

Macron had criticized Germany's disproportionate economic power in the EU in a Monday interview with Germany's Funke media group, saying the current situation "isn't good for Germany's own economy, nor for the economy in the eurozone," he had said.

'Savage globalization'

Le Pen meanwhile promised to suspend all immigration and shield voters from what she called "savage globalization."

"I will protect you. My first measure as president will be to reinstate France's borders," Le Pen told a crowd of about 5,000, prompting the National Front's (FN) traditional "This is our home!" chant.

"The choice on Sunday is simple," she said. "It is a choice between a France that is rising again and a France that is sinking."

"Mass immigration is not an opportunity for France, it's a tragedy for France."

The crowd booed the EU and its border-free Schengen area, from which Le Pen has said she would remove France if elected.

"The French sometimes have fewer rights than foreigners - even illegal ones," she claimed.

Repeated interruptions

Scuffles broke out between 60 to 80 anti-FN protesters and police near the Zenith concert hall in northeast Paris ahead of the rally. Police fired teargas at the protesters, as some demonstrators hurled chunks of wood.

During Le Pen's speech a young woman jumped on the stage and was carried away by security, while a topless woman later shouted out from the middle of the concert hall in an apparent protest against the candidate.

One FN official, Jean Messiha, said he saw several Molotov cocktails being thrown.

Melenchon's Resistance

Jean-Luc Melenchon, a left-wingcandidate, cruised into eastern Paris on a barge on Monday.

"Resistance! Resistance!" supporters chanted.

Hundreds of people flocked to the banks of the Canal Saint Martin to show their support for the firebrand vowing to take on the "oligarchy" and the "ultra-liberal" EU.

As the charismatic leader of La France Insoumise (Unbowed France) finally came into view, a brass band on deck struck up the 1960s hit "Can't Take My Eyes off You."

The 65-year-old political veteran has surged from behind in the final stages of the campaign to become a serious contender for one of the two top spots in the first round of voting on Sunday.

Melenchon - a former minister who quit the ruling Socialists in 2008 - in the last election in 2012 was tipped as the "third man" but hemorrhaged support in the final stages to finish fourth, behind Le Pen.

"Keep the fire of rebellion burning inside you," he told supporters.

Fillon hanging on

Conservative candidate Francois Fillon spoke to voters in Nice on Monday.

Fillon has recovered some ground after being hit by a scandal over hundreds of thousands of euros of public money he paid his wife while employing her as his parliamentary assistant.

The official campaign commenced on April 10 and will end at midnight on Friday, April 21.