« Résistance! Résistance! Résistance! »

As Jean-Luc Mélenchon's strides on to the stage in Besançon, he bellows the battle cry for generations of political street-fighters. The Front de Gauche's presidential candidate is difficult to ignore. At the pulpit, he gesticulates wildly, jabs his finger violently as if to spear some futile right-wing argument; he pauses, jokes, glares.

Rather than chained to the microphone, he can't stand still, wrenching the speech out, taking a pace to the left, then the right, of the rostrum. Or, « Left, and the other direction », as he prefers to say, not without a wry smile.

He's more than the focus of the evening's rally; he's the centre of its gravity. His stage-presence casts a shadow over the rest of the speakers. That has a double-edged value: Mélenchon clearly embodies the far-Left's hopes of counting on the national stage, but it means the other members of the Front de Gauche (including the French Communist Party) are sidelined.

His goal, though, remains theirs: this is Class War. Earlier in the day, Mélenchon was outside a scooter factory, threatened with job-cuts as the owner shifts production overseas. « The bosses, the powerful, they control your lives. And then they relocate! To satisfy the appetite of capitalism! » he tells the few who have come to listen. He pays tribute to the trade-unionists who have turned up, despite what that'll mean for their job prospects; to mark his visit, the factory has been closed. Ostensibly, to save money; Mélenchon insists it's to avoid him getting his message across to them. « It's the crack of the bosses' whip! »

Mélenchon has always been known for his principles; after 34 years spent on the left of the Socialist Party, he went his own way in 2008. It wasn't Left-wing enough for him. Having launched his own Left Party, he's now combined with the Communists (amongst others) to form a common Front de Gauche (Left Front).

Mélenchon: A firebrand, but an eloquent one.

He is clearly the motor behind this campaign: people have come to see him, to see him perform. Over 4000 have made the trip to Besançon for the rally, a good turnout. Without him, without his charisma, the left of the Left would be left leaderless.

That combination of dynamism and stubborness plays to his advantage. Daniel has travelled 90km to the rally from Dijon. With his bright red scarf, the retired ouvrier (worker) is clearly not a floating voter. And he's delighted at how Mélenchon has pushed the Socialists further to the Left, launching their attack on the world of Finance this week, too. « He's helped redden François Hollande's position. We need a real Left to take power ».

Mélenchon's reply to that lurch leftwards from Hollande? « Welcome to the club! We feel less lonely now! But you'll need more than a pop-gun; they're real adversaries! »

The words pour from him. But it's not simply a stream of invective; Mélenchon is an eloquent speaker, on stage and in the campaign bus. Quoting – as is his tradition – Victor Hugo's Les Misérables as he concludes, « the cobblestone is the best symbol for the people. You walk all over it every day, until the day it falls on your head. »

Like many politicians, he can talk the hind-legs off a donkey. But he's also mastered the art of good public oration; looking back through our interviews, his best phrases clock in at bang on 15 seconds. Perfect for a soundbite. That talent has become a burden. Mélenchon – with his big-mouth and eminently quotable discourse - has long been a media favourite; what can you expect, when he called last week the far-right Front National leader Marine Le Pen « semi-démente » ('half-insane')?

And while he resents the way that obscures his real message, it seems he can't help himself: « the Front National, they're neurotic, they're obsessed with immigrants, they're mentally ill », he adds this week, clearly unrepentant. In essence, though, his hatred of the far-Right movement, as well as its dynastic rulers, is far-from phoney; it's visceral, the heritage of decades of political struggle. « They're anti-immigrant, not anti-bankers. They're just the bosses' boot-lickers », he tells the crowd.

The problem is that Marine Le Pen is far ahead of Mélenchon in the polls; the working-class is fertile terrain, tempted by her « French-first » policy. Mélenchon's goal is to ensure his supporters convince their co-workers that « [Voting] Front National is class betrayal. They're conning the working classes. They don't understand this country. People who say 'Mélenchon's not xenophobic enough to get through' ... that shows their contempt for the working class ».

As the crowd choruses the workers' hymn L'Internationale – followed by the Marseillaise, to underline Mélenchon's mixed heritage, if not his divided loyalties – the Front de Gauche's candidate is in a dilemma. Having gambled on going it alone to fight for workers' rights, now his real battle is persuading workers that he's the best candidate to represent them.

By Luke Brown

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