Yvette Cooper Jeremy Corbyn Liz Kendall
Labour leadership candidates Yvette Cooper (L) and Liz Kendall (R) applaud new leader Jeremy Corbyn  Reuters/Stefan Wermuth

When Jeremy Corbyn gets nobbled, as seems sadly inevitable, it will be by his own team. It'll have been by the concerted backstage work of an ugly coalition of the soft left establishment, an expedient alliance of moderate interests that have always held the democratic process in genteel contempt.

When it happens, the deafening chorus of "I told you so" will ring out hotly and loudly from this same vainly aspirational dung-heap, as the hatchet-men claim he was never up to the challenge of party leadership.

This will lead to a safe pair of cardboard hands for 2017, a Stella Creasy maybe, or an Chuka Umunna, and there won't be a peep from the commentariat on either side of the aisle wondering why the new shadow cabinet is mostly men. And after that, the only really politically enthused segment of the population we've had in a generation will sublimate away forever.

Corbyn is a rarity in the modern political marketplace: a man with demonstrable convictions that he sticks to and articulates honestly and earnestly
- Tom Mendelsohn

It doesn't have to be this way, even though it will. I'm not going to pretend your man Corbyn is a transformational figure, particularly, or one without his share of baggage.

What he is, though, is a rarity in the modern political marketplace: a man with demonstrable convictions that he sticks to and articulates honestly and earnestly. This is his greatest strength, because believers can build a movement with momentum around him, and his greatest weakness, because they're not the convictions that the establishment wants.

The attacks he's weathering from a ruling class incensed at his very existence are histrionically out of rational proportion. His every decision is scrutinised with chops-licking glee by enemies nominally on the left who are putting more effort into finding ways to describe the first ever shadow cabinet containing a majority of women as sexist than they ever do into attacking an economically rapacious Conservative Party (one that, lest we forget, presides over a cabinet featuring just seven women).

When he's not being criticised for sexism, he's being savaged for floating (floating, mark you. Not prescribing by authoritarian party diktat) ideas that might help women, such as segregated train carriages. And when he's not doing that, he's being insidiously fingered for anti-Semitism by association. His accusers are always careful not to suggest he hates Jews but, they say, shaking their heads in serpentine mock-bewilderment he does keep very funny company.

If that seems like a lot of negativity in an article that's meant to extol the virtues of the new leader of the Labour Party, as someone who passionately believes in the possibility of a fairer society and the importance of getting the private sector out of government services, I'm finding it increasingly tough to make all the many excellent positives over the chorus of disdain from people technically on my side.

Every conversation, no matter how sincerely you want it to be about progressive tax policies, abolishing austerity and establishing a society that takes pleasure in the care of others, is sabotaged by people who should know better.

The preliminary caveats become the whole conversation, which of course is what Rupert Murdoch, Lynton Crosby and David Cameron want. The powerful, simple message of investment in public services and redirecting vast corporate profits towards the poor upon whose backs they are inevitably built is lost in a flurry of mischievous hand-wringing.

Can Corbyn win an election? I don't know. Can George Osborne? Could the photocopy-of-a-photocopy Blairite brains trust Jezza had as opposition in the leadership contest have won an election? The press would have savaged each of them just as hard (well, the right-wing press would have done) and none of them had any convictions to fall back on by way of fightback.

Fact is, for many Corbynistas, winning isn't the only criterion of success. In a party which has clearly badly lost its ideological way, in which winning at any cost is preferred to achieving real change, a calculation is made that we'd rather have the chance to move the goalposts back in a leftward direction.

This is the concept of the Overton Window, a chunk of political theory that posits only a certain amount of political spectrum is open for debate at any one time. This window is now so far to the right that the Parliamentary Labour Party does not consider it necessary to properly contest austerity measures that go far beyond even Thatcher's wildest and most unpleasant dreams. If nothing else, having a principled leftist leading the opposition will bring the parameters of debate back from the howling edge of the neoliberal abyss.

Look what Corbyn has achieved already, in three days of office. Within minutes of winning the election, he was on a pro-refugee march. A day later, and a rattled David Cameron makes a sudden appearance at a Lebanese refugee camp; if this isn't a sign that the new Labour leader is forcing the conversation to change, I do not know what else it could be. Just imagine Yvette Cooper having anything like that kind of clarity of vision, let alone clarity of speech.

The thing is, we need Jeremy Corbyn. He's the closest thing to a movement the left has got, and our only shot at bringing the world back round we'll have in decades. Whether you personally think he is charismatic or not, in his own quiet way, he inspires people in their tens of thousands with his plain talk and simple beliefs. I don't think it'll be easy and I do think it will rest on his ability to step up to the biggest leagues, but I believe he can win, and I invite you to do the same.

Tom Mendelsohn is a freelance journalist based in London. Follow him on Twitter: @Tom_Mendelsohn.