The past decade has not exactly been short of surprises in Greek politics. But even to seasoned observers, the election of Stefanos Kasselakis as the new leader of Syriza, Greece’s main opposition party, stands out as one of the strangest developments yet.

A former banker now leads a party founded on an anti-banker platform

A 35-year-old former Goldman Sachs trader with no prior political experience, Kasselakis has shattered conventional expectations by defeating his rival, Effie Achtsioglou – a party insider favoured by many senior officials – with a 56.69 per cent majority.

His victory comes as Syriza wrestles with internal divisions and existential questions. It is most likely because of this upheaval that Kasselakis – the most unlikely of left-wing candidates – was even able to challenge for the leadership of the party.

Living in Miami rather than Greece until earlier this year, Kasselakis is a political newbie who was virtually unknown to the Greek public until recently. That changed when he released a viral video announcing his candidacy and outlining his vision for the party and the country. Just 19 days after the video, he led the first round of the leadership contest, getting nearly 45 per cent of the vote.

Social media has been central to Kasselakis’s rise. The video not only introduced him to the Greek public but ignited broader interest in the leadership contest which until that point looked very stale. His campaign was then helped by significant coverage from the mainstream media, which focused on his lifestyle.

Here, he is again an oddity for Greek politics: educated at the University of Pennsylvania in the United States, Kasselakis worked for Goldman Sachs before founding his own shipping company. He has been outspoken about LGBTQ rights in Greece and is in a civil partnership with an American, Tyler McBeth, making him the first openly gay leader of a parliamentary party in the country’s history.

But there is more to Kasselakis’ victory than a well-thought-out campaign on social media: Syriza has been in a state of flux following two significant electoral defeats and the resignation of its long-time leader, Alexis Tsipras.

Despite there being more experienced candidates than Kasselakis, many of the party’s rank-and-file members felt the need for change. His candidacy also received support from influential party figures, like the outspoken and controversial Pavlos Polakis, who belongs to the populist left tendency of the party, adding another layer of complexity to the internal dynamics of the contest.

Then there are the elements of the business and media world who have been making approaches to Syriza for the past decade. A candidate like Kasselakis would be ideal to move the party further away from its old, more radical roots, and towards a more palatable, business-friendly position.

This doesn’t resolve however the ideological paradox: a former banker now leads a party founded on an anti-banker platform. This has led to tensions with the party’s old guard, who view his candidacy as a major departure. But his supporters claim that this is the only solution to the existential crisis they are facing in the post-Tsipras era – and that the party has been searching for a new direction, which Kasselakis’s leadership could potentially provide.

What this new direction is, however, is a bit of a mystery. With no debates or big speeches under his belt, we only have his videos, statements and interviews to decipher what Kasselakis actually stands for.

He has declared that he is a ‘patriotic leftist’, but promised to do away with conscription in favour of a professional army. He is obviously pro-LGBT rights but also cultivates a very macho image.

And while he clearly preaches from the social-democratic gospel, his background and the clear influence that the US Democrats have on his campaigning style, has left many traditional leftwing supporters in doubt – if not outright despair – at the direction the party seems to be heading in.

Perhaps the most interesting accusation levelled at Kasselakis is that he is a mirror image of PM Kyriakos Mitsotakis, who consistently prioritises comms and message control over substance. But as the resounding victories of both Mitsotakis and Kasselakis show, their style of campaigning works. It remains to be seen if there is anything more than clever PR in Kasselakis, and what the future holds for the Greek political landscape.