The Tasmanian era is over. Since its formation as a national party in 1992, the Australian Greens has been led by Tasmanian senators: first Bob Brown and then Christine Milne. This is an unsurprising fact given that the island state gave birth to the Australian environmental movement as a political force. The 1972 campaign to save Lake Pedder in Tasmania’s south-west led directly to the formation of the world’s first green party, the United Tasmania Group, and in the 1975 federal election the young Bob Brown stood as the UTG’s No 2 Senate candidate. He polled 112 votes.

Greens supporters will hope that the election in May of Victorian senator Richard Di Natale as party leader will lead to a further consolidation of the Greens as a mature political force with national representation and clout. In every election that the party has contested, its decline and eventual demise has been predicted by the mainstream media, and its support underestimated or written off. In 2001 when I wrote a Quarterly Essay on the Greens as a coming force (‘Groundswell: The rise of the Greens’), many people expressed surprise. At that time the Australian Democrats were the third party force in the parliament with eight senators, but a close analysis of voting trends over the previous decade indicated that the Greens were set to replace them. The Democrats’ base had always been one of soft middle-class disaffection, while the Greens were part of a growing international movement with significance beyond local preoccupations; they could argue for historical momentum, and so it has proved. In addition, the drift to the right of the ALP under the pressure of the neoliberal ideological ascendancy in the ’90s allowed the Greens to siphon off the progressive vote from both major parties, but especially from the left of the ALP.

Over the past two decades, Brown and Milne have each led the party with courage and steadfastness; they stared down the sneering commentary of the media while earning the enmity of both major parties. Both were already experienced operators when they reached the Senate; they had cut their teeth not only as activists in Tasmania’s forestry wars but also as participants in coalition state governments, both Labor and Liberal, from which they had won significant concessions. It was no easy task for Milne to replace the charismatic Brown, a once-in-a-lifetime politician, but unlike the Democrats’ Cheryl Kernot and Meg Lees, both of whom imploded as leaders, Milne displayed an iron resolve in her dealings with government.

Milne’s succession was always going to be a three-way contest between Richard Di Natale, WA senator Scott Ludlam and the member for Melbourne, Adam Bandt. There has been much speculation as to why Bandt didn’t run or stay in his deputy leader role, and questions have been asked as to whether Milne ambushed his candidature by her sudden announcement of retirement. In the wash-up it’s unlikely to matter. Bandt has successfully applied a demanding Obama-style model of community politics to his electorate, and in the short term he will need all his energies to retain his seat. Moreover, since the Greens are a Senate-based party it makes sense for their leader to be anchored there.

Di Natale is only 45 and, barring unforeseen events, is likely to be leader for a long time. His election has mostly been welcomed by media pundits who describe him as being more “mainstream” in appeal than his predecessors, less focused on environmental issues than on social justice, though the Greens’ updated website features an image of him in the middle of a rainforest, and in any case the Greens have always maintained that the environment and social justice are inextricably linked. Nevertheless, there appears to be a consensus that Di Natale is more likely to move the Greens towards some kind of “centre” (never defined) and to negotiate with government. At his press conference on 6 May, he was at pains to declare himself “no ideologue” – the implication being that his predecessors were – but this may have been a rhetorical feint designed to disarm critics in the short term.

One thing is clear: he has a kind of Aussie blokishness, a robust masculine presence that is not normally associated with the Greens. A devotee of the Australian religion of sport, he is a keen surfer and cricketer with six years as an Australian Rules footballer in the high-level VFA competition. Nor does it hurt that he has an immigrant background. His Sicilian father was an electrician while his mother emigrated from San Marco in southern Italy. Though he is no forestry activist in the Brown–Milne mould he has been an activist nonetheless, not least in his role as a doctor working in an Aboriginal community and on HIV prevention in India. Former Greens staffer Ben Oquist, who fell out with Christine Milne, has labelled Di Natale’s 2014 trip to West Africa to investigate the Ebola epidemic as “a new kind of activism”. Oquist describes Di Natale as a good negotiator who is “outcome focused”, citing his success in negotiating with the Gillard government on a $5 billion program for public dental health.

Any change in a party’s political guard presents opportunities for a reset in the public imagination. The likes of Barnaby Joyce persist in trying to characterise the Greens as a privileged, arty inner-city elite (everyone drinks lattes now, Barnaby – try lining up at a coffee cart with some tradies), and while the largest proportion of the Greens vote is city based, paradoxically the old guard of the Greens came mostly from staunch rural stock. Brown is the son of a country policeman, Milne the daughter of a small dairy farmer, and one of the party’s founders (and Lock the Gate activist) Drew Hutton the son of a country butcher. Di Natale might now live on a small working farm outside Melbourne, but the new Greens leaders are more urban in their backgrounds and preoccupations. Bandt and newly elected co–deputy leader Larissa Waters are former lawyers, and indeed the young Bandt followed a path similar to that of many young Labor industrial lawyers with political aspirations. (Both Julia Gillard and Bandt worked for Slater and Gordon.) Di Natale owns to coming from a Labor-voting family, and it’s not hard to imagine him and Bandt, and Milne for that matter, as Labor politicians in another era.

Bob Brown and Scott Ludlam, the new co–deputy leader alongside Waters, are a different breed again in that it’s difficult to imagine either ever belonging to one of the major parties, but it is politicians of their ilk – nerveless political outliers – that hold the keys to the Greens’ core vote. Ludlam, a former graphic designer, is the Greens’ spokesperson on cities and technology. His election as one of two new deputy leaders sends an important signal, not least to the youth demographic where Ludlam has emerged as a hipster with gravitas. His Senate adjournment debate speech of March 2014, one of the most trenchant and politically effective speeches to be made in that chamber in recent times, had all the teeth and bite that Labor’s current efforts lack. When Ludlam attacked Abbott in the rhetoric of a street fighter, he released a wave of pent-up frustration from those who have despaired of Bill Shorten’s ineffectual hectoring and want more grunt from their opposition parties. Within ten days the speech had scored more than 700,000 hits on YouTube and given Ludlam a national profile.

Meanwhile, in Western Australia Ludlam has led the Greens in developing their WA 2.0 plan for cities, working with the Property Council of Australia on a model of affordable medium-density housing with alternative energy, good public transport and bushland corridors. His strong presence on social media, his support of Julian Assange and Edward Snowden, and his forensic work on the National Broadband Network and the new metadata surveillance legislation – he has hosted “CryptoParties” to teach vulnerable users about encryption and online anonymity – have won genuine admiration among millennials. He may be too much of a political outlier to ever be party leader and a “mainstream” spokesperson on “working families” but his role is crucial to the integrity of the Greens, both real and perceived.

Larissa Waters is a lesser-known quantity. On current form it’s hard not to presume that she is there for gender balance, but she has brains, looks and charm and has presented well in national forums like the ABC’s Q&A.

If Di Natale’s role is to project mainstream appeal and boost the party’s vote to a crucial 20%, he must ensure that he doesn’t go down the path of the Democrats in the process and gain a short-term popularity at the cost of his core constituency. Any deal done with the Abbott government must look like a win for the Greens. It’s sobering to look back on the careers of Cheryl Kernot and Meg Lees, whose compromises with John Howard, firstly on industrial relations and then on the GST, arguably destroyed their party’s base. Drew Hutton recalls Bob Brown remarking at the time that, in effect, “if you’re going to hang in close to the Liberal Party and mitigate their policies, rather than hang in close and mitigate Labor’s, you’re actually starting from such a low base on things like the environment and industrial relations that you’re going to get yourself into trouble. You have to keep faith with your constituency.”

Di Natale might do well to remind himself that those elements in the media who applaud his mainstream appeal have never approved of the Greens in the first place and continue to impugn their legitimacy. The party is frequently portrayed as holding the Senate to ransom, but less commented upon are the disparities revealed in recent state elections. In Victoria in 2014, the Greens won two seats in the lower house from 11.48% of the vote, while the Nationals won eight seats on a vote of 5.53%. In the NSW state election of 2015, the Greens won three seats in the lower house coming off a vote of 10.29%, while the Nationals took 17 seats on a vote of 10.55%.

The core vote of the Greens has been estimated at a stable 6–8%, with the rest being attributed at any one time to a volatile protest vote against the major parties. In the 2013 half-Senate election, for example, following the party’s collaboration with the unpopular Gillard government, the Greens vote dropped by 4.46% to 8.7%; a significant protest vote went to other minor parties, with the Palmer United Party polling 4.91%. When 1370 ballot papers in Western Australia were found to have been lost and the High Court ordered an unprecedented rerun of the poll in that state, the Greens’ vote rose dramatically from 9.5% to 15.6%. In the six months between the two elections, the federal government had brought down a radically unpopular budget, Ludlam had made “that speech”, and the Greens campaign machine had mobilised from across Australia to focus on WA. The result? A dramatically increased protest vote, which poses the question: at what point does a so-called protest vote cease to be a temporary protest and develop into a cross-generational loyalty? As Di Natale remarked during an interview with ABC’s 7.30, there are now people who have voted for the Greens for the second, the third and the fourth time.

The problem, as always for the Greens, is getting their message across to the wider electorate. Peter Dombrovskis’ exquisite photographic study of the Splits on Tasmania’s wild Franklin River was a romantic image that spoke to many, and the advertisement in the national papers that featured it in full-page colour had a galvanising effect during the 1982–83 campaign to save the river from hydro-electric flooding. Local campaigns have the power to sway regional communities – the anti-fracking movement helped the NSW Greens to win the state seat of Ballina and come close in Lismore – but in the broader sense the Greens are yet to capture the political imagination of a significant proportion of the electorate.

The Greens have to deal not only with vested interests but also, and more pervasively, with a kind of cultural antagonism, bordering on hatred, that wants to make them the scapegoat for every perceived ill and every personal resentment of an increasingly discontented electorate. That resentment is fostered by right-wing elements of the media who portray them as privileged and eccentric elitists: hippies, bicycle riders, vegetarians and food faddists who love trees more than jobs and whales more than people. Sometimes scruffy and feral, sometimes urbanely hip and affluent, but always self-indulgent, they are resented for their perceived sense of moral superiority. Above all, in Australia they are disliked because they have dared to assert themselves against the stifling and often mindless conformity to the norm. Other people have to cave in to the pressure to conform, why shouldn’t they? None of this has anything to do with the established science on global warming and a growing international consensus, and there’s a sense that the Greens are always conducting an unspoken argument that’s not about policy but perceptions of identity, of who they are, and they’re not us. But the Greens have become accustomed to this, and in any case they argue that much of the cultural antagonism is generational and their strong support from the youthful demographic is ultimately going to “wash through”.

To be fair, few politicians manage to capture the public’s imagination in a positive sense. One of them was Kevin Rudd, in 2007, when he declared climate change to be the great moral issue of the times. In that moment a sizeable portion of the general public was prepared to grant Rudd something they won’t concede to the Greens, namely moral leadership. There was a spike in public support for the Rudd view until Rudd lost his nerve. When bullied by the Coalition and vested interests, he retreated, and the momentum that had built rapidly deflated like a giant balloon pricked by political cowardice.

The Greens, on the other hand, have demonstrated their stamina. Like them or not, they are a tough lot who have rebounded from a number of setbacks. They don’t have much cover – unions, business – but their morale is strong. Says Ludlam: “We know who we are and why we’re here. Labor doesn’t.” But it’s also true that within their own supporter base they have critics who feel they have become too risk averse, lacking the kind of bold militancy that saw Bob Brown and the then NSW Greens senator Kerry Nettle make a stand in 2003 against George W Bush’s presence in the Australian parliament. Contrary to the media hosannas for a more mainstream Greens leader, Guy Rundle has argued in the Monthly for the Greens to embark on “a renewed and more visible militancy”.

Militancy or mainstream? Such is the fork in the road for Di Natale. Labor has been limp in Opposition, but the Greens too have so far failed to capitalise on the government’s extraordinary confusion and, other than the stirring moment of Ludlam’s adjournment speech, have failed to produce a strong spokesperson who can crystallise areas of public sentiment and anger. New leadership under Di Natale presents an opportunity for the Greens to supplant Labor when it comes to taking ownership of a credible alternative model of the modern economy. Ben Oquist, now director of strategy at the Australia Institute, points to both Di Natale and Bandt as strong on economic issues and believes both are likely to increase their profiles in Treasury and Finance portfolio areas. If so, this would be overdue. Di Natale was chair of the Senate select committee of inquiry into the government’s National Commission of Audit, where he played a part in debunking the claims of the audit’s chair, Tony Shepherd. The new Greens leader may decide to take on the role of economic spokesperson himself.

To borrow from George Myerson in 2001’s Ecology and the End of Postmodernity, the Greens need to convince a sceptical public that they are not reactionaries, Luddites and spoilers but the leading proponents of a new and urgent “mainstream modernity”, one based on innovative responses to the science of climate change, to population growth and the pressure on cities, not to mention the crisis of growing inequality and of weakened community that threatens to undermine the perceived legitimacy of liberal democracies. Ecology, as an understanding of man’s relationship to nature, is a way of seeing these as inextricably linked, a new grand narrative in which a once suspect science that produced industrial pollution now offers a diagnosis and a series of alternatives that can begin to redress the damage. In that sense, writes Myerson, the environment movement is not anti- or post-industrial but the herald of an industrial future that new-wave ecologists like Paul Hawken, Amory Lovins and Hunter Lovins have labelled “natural capitalism”.

To many voters it would seem a novel idea that the Greens might support any kind of capitalism, so identified is the latter with the big mining industries, but if the Greens are going to attain that magical 20% that will make them a major party they must begin to rebrand themselves as the new-generation capitalists of a sustainable and more equitable future.