Zack Polanski has become something of an internet phenomenon of late.

Despite being the deputy Green leader since 2022 and a member of the London Assembly since 2021, he was definitely not among the most well-known politicians, even within his own party.

But something changed in May when, after years of membership, he announced he was running to lead the Greens on a socialist ticket, as an “eco-populist”.

Although the party has not officially declared how many members it has, leaked figures suggest the membership grew by 8,000 in the weeks after his declaration – taking them to at least 65,000.

Rumours of potential defections from disillusioned Labour MPs have even been swirling, although any concrete details have been kept under wraps.

He told HuffPost UK he’s slowly drawing in voters from across the political spectrum – including Tories – and winning back old supporters, including those who helped establish the precursor to the Greens, the Ecology Party.

Green sources also say Polanski was already very popular within the party when he decided to throw his hat into the ring earlier this year, and he had reportedly been encouraged to put himself forward for leadership for some time.

He’s since gone viral with his proposals to introduce bold leadership and break through the malaise around Westminster politics.

But his campaign hit a small snag this week.

Hours before we spoke, former Labour leader Jeremy Corbyn and ex-Labour MP Zarah Sultana announced they were launching a new party on the left and invited everyone to join, for free.

By Friday, the group claimed to have nearly 230,000 sign-ups – eclipsing the so-called “Polanski surge” within the Greens. But Polanski did not seem too concerned.

“I’ve read their statement and I can’t see a single thing in there that’s not Green Party policy or doesn’t align already with the Green Party,” he said.

He then suggested those two MPs should just join the party with those values that already exists – the Greens.

He also warned that one downside of running a party very democratically – members get to choose the name of Corbyn’s new group – is that it ends up operating rather slowly and so may take a while to get off the ground.

That criticism of acting in a rather glacial pace is often pitched at the Greens, from insiders and outsiders alike.

Corbyn’s party would have one advantage over the Greens if Polanski wins the leadership contest: its leader would be an MP in the Commons.

Polanski does not see that as a major sticking point in this leadership race though, even as his opponents, running on a joint ticket, both have seats.

He said Westminster is “dull” and it’s actually a “huge positive” to be able to tour the country to spread their message without being tethered to a constituency.

Although, of course, the politician said he would love to be an MP and will be standing at the next general election – but he still insisted: “Westminster is an important place for scrutiny, for accountability and for democracy. It’s a very dull place, not a place for storytelling.”

“I think we need at the top of the party a communicator who can speak to the country, who can excite, and inspire people,” he said. “And I think parliament at this core, is not an exciting, inspiring place, and that is no criticism of our MPs or indeed any MPs.”

What about Nigel Farage, the leader of Reform UK, whose party has gone from strength to strength and now dominates the polls after they got five MPs elected last year?

Polanski said he thinks Farage was having more of an impact before he became an MP.

“It’s very much more difficult for him now to criticise the establishment when it’s very clear that he’s at the heart of that establishment,” Polanski said.

When it’s pointed out that Farage has an avenue to hold Starmer to account now he’s in the Commons, he said: “I don’t think I’ve seen any clip of Farage holding Starmer to account.”

He also claimed Farage is a millionaire who is “pretending to serve working class communities but actually serving billionaires”.

“I think Reform have got real problems ahead of them in terms of where their donations come from and the people who are supporting them, who have not been exposed yet to the transparency of that,” he said.

Despite his words of criticism for the Clacton MP, it’s hard to deny that the two are indirectly tethered as both are seen as populists – although Polanski calls himself an “eco-populist”.

And, according to the London Assembly member, Farage’s anti-immigration stance and support for nationalisation does not reflect populism.

“I don’t believe Farage is a populist. I don’t think we should cede these words to the right,” he said. “Populism, for me, is about the 99% versus the 1%. Farage is protecting that 1%.”

Starmer, of course, is his main political target though.

“I think the number one goal is to make the Labour Party more scared of losing vote seats to a Green Party than to Reform,” he said.

Pointing to their welfare cuts, Polanski said: “I find it intensely frustrating that this Labour government get described as the sensibles or the adults in the room when the consequences of their decisions are literally killing people and despite the fact that all the evidence is pointing to what they are doing is creating more inequality in society.”

Of course, this is a criticism levelled at Starmer across the board – that Labour is just not making the right decisions at the right time, particularly over Gaza.

But the Greens are not fully aligned, either.

Insiders fear the party is not doing enough to seize the pro-Palestine vote, which could go to Corbyn’s group instead, while old tropes that the Greens are “too white” continue.

However, Polanski said: “People of colour are voting for us, as polling showed last week.”

He said the Asian vote has increased by around 17% for the Green Party, pointing to FocalData stats.

He added: “So I think the kind of old tropes about the Green Party just aren’t true anymore.”

HuffPost UK was unable to find that particular data.

Polanski has also been at the centre of some negative coverage online, sparking speculation that not everything is as rosy within the Greens as previously indicated.

The Greens’ current co-leader MP Adrian Ramsay, who is running against Polanski with Green MP Ellie Chowns, was asked if he liked his opponent during a joint debate on LBC after all of their agitated televised exchanges.

Ramsay refused to say initially, even as Polanski insisted he likes Ramsay.

Polanski told HuffPost UK that he was “upset” at Ramsay’s response.

He said: “I was… upset last night when he refused to say that he liked me. He did eventually get there.

“I also shrug my shoulders and say, that doesn’t matter. We work perfectly well together. These are professional relationships, and I like him.”

But he notably added: “But, you know, I’m a human being. And if someone doesn’t like you, then, yeah… that was… it was bizarre.”

Ramsay – and Chowns – are promising to be “insurgents” in politics, too, just in a different way to Polanski.

Chowns previously told HuffPost UK that Farage relies on “complete distraction politics”, adding: “I really don’t think that we win Green power by aping Donald Trump or Farage in any way.”

While the Greens may have just four MPs in parliament right now, there’s no denying that public appetite for something a little different is growing.

But which direction will the Greens end up moving towards: headline-grabbing populist tactics, or sticking to slow-and steady establishment strategies?

Only the members can decide – but it’s clear results it could create a ripple across Westminster.