PARIS — France's far-right leader and presidential hopeful Marine Le Pen suspended her field campaign on Tuesday as she struggled to acquire the necessary mayoral pledges required to make it on the ballot list.

French presidential candidates are required to gather 500 sponsorship letters from mayors in order to be officially eligible.

Marine Le Pen, the candidate for her far-right National Rally (RN) party, has so far only managed to secure 393 such letters, according to a tally kept by the Conseil Constitutionnel.

The cut-off date is March 4.

Le Pen is polling second to President Emmanuel Macron, who has yet to officially announce his candidacy, at around 16-17% in the first round while the incumbent is projected to gather 24-25% of the ballot. He is then forecast to win the run-off with 56-57% of the vote.

Only six candidates have so far obtained the required 500 pledges. These include Valérie Pécresse of the right-wing Les Republicains, the Socialist Party's Anne Hidalgo, the Greens' Yannick Jadot, the Communist Party's Fabien Roussel, centrist Jean Lasalle and Macron.

Candidates on the fringes have however struggled to pass the necessary threshold.

Far-left leader Jean-Luc Mélenchon of La France Insoumise has 442 pledges. Eric Zemmour, a challenger to Le Pen on the far-right, has 350 letters and canceled a planned campaign trip to the island of la Reunion last week to man the phone and secure additional pledges.

He told reporters that "it's obviously a hindrance, it takes a lot of time, everyone is mobilized."

Zemmour is currently polling third with Melenchon fifth. Both Zemmour and Le Pen have called for a 2016 reform that lifted the anonymity of the pledges to be overturned.

"Mayors are under a lot of pressure from departmental councils and communities of municipalities. The lifting of anonymity is terrible for democracy, as we can see the three of the most important candidates risk not getting their pledges," one of Le Pen's spokesperson, MEP Jean-Lin Lacapelle said on Tuesday.

Another member of her team described it as a "red alert". "The very idea of her not being able to run for the presidency would pose quite a democratic problem," Sébastien Chenu said.

"She represents millions of voters and remains the only one who can beat Macron," he added.

The party saluted the initiative earlier this week of three mayors in the southern department of the Var to choose who to give their pledge to between Zemmour, Le Pen and Mélenchon through a ballot system.

"They have found an original way that we hope will encourage other colleagues to sponsor," the RN said in a statement on Facebook.

Prime Minister Jean Castex called on Tuesday for elected representatives to "bring their sponsorships" to the candidates in the running, stressing that such a step "is not automatically synonymous with political support".

Many mayors, particularly in rural areas, are reluctant to publicly display their sponsorships.

Castex said he would receive associations of local elected representatives on Thursday morning to "discuss this situation together (...) because it is a deeply democratic issue". — Euronews