The year 2010 appears now as a high-water mark for the Australian Greens. The party secured sole balance of power in the senate, won almost 12 per cent of the primary vote in the lower house, and in Adam Bandt won its first seat in the house of representatives. While Bandt has since fortified the seat of Melbourne – privately, Labor concedes his supremacy – the Greens’ electoral fortunes have oscillated.

The balance of power won in 2010 was lost to successive parliaments’ unpredictable mix of minor parties and independents in the senate. In 2012, the Greens lost its broadly respected leader, Bob Brown, to retirement. Increasingly, the Labor Party has successfully, often cynically, exploited perceptions of Greens’ sanctimony – though the Greens has had its share of substantive scandals. The dream of a 15 per cent primary vote, and a lower house colleague for Bandt, remains unfulfilled.

But Brown says media commentators have long underestimated the appeal of the Greens, and the party’s potential. “I’ve seen the Greens do well, and I’ve seen them do badly,” he says. “But I think the Greens could be a surprise this year. I greatly respect Richard Di Natale and his team. They are not divided at all on climate change. But the LNP is. Labor is. The Greens aren’t.”

When I spoke with Brown he was in Brisbane, the latest stop of his protest convoy, which started in Hobart and is travelling all the way to the Galilee Basin in western Queensland, the site of the proposed Adani coalmine. The convoy will then return south, ending at Parliament House on May 5. “A prime reason for this convoy is to keep the Adani mine and global warming in the public eye as [people] go to the ballot box,” Brown says.

Queensland’s most read newspaper, The Courier-Mail, condemned the convoy and reported that one of its supporters likened coalminers to Nazis in a private Facebook group. There was a whiff of Sir Joh in the theatricality: “You have taken offence that we have labelled you and your convoy ‘blow-ins’ but many of your protesters do not live in this state. History shows Queenslanders do not bow down to those from interstate who try to tell them how to live their lives.”

Local jobs versus the environmental future. Practicality versus abstraction. The working class versus southern elites. Climate change is bound and gagged by the culture wars – and Bob Brown’s convoy was a perfect encapsulation. Brown quickly, and emphatically, condemned the witless Nazi reference – but he also wondered about the journalistic integrity of quoting anonymous Facebook comments as being representative or useful. It was recklessly inflammatory, he told me, and one could find comments calling for the killing of environmentalists in the comments on Liberal Party members’ Facebook pages.

“Since the rolling of Turnbull, there is a whole pile of voters who said they would never vote Labor who are shocked and angry and looking for an alternative. They need someplace to go.”

“This election should be about our future,” Brown said. “Our children’s future. There’s no discussion here about the future of Australia’s kids. There’s no debate about all Australians’ insurance costs going up hundreds of dollars because of floods and fires, drought and the drying up of the Murray–Darling Basin – where we’re talking about the majority of food production there being lost because of the burning of coal and oil. The argument is reduced to the vilification of the others.”

Along with Adam Bandt, six of the Greens’ nine senators are up for re-election. There’s a lot to lose, and senior Greens figures aren’t bullish about their prospects. A senior Greens source defined success to me as: “Retain, retain. Keep our senators and retain Adam. We’ve been very focused on retaining that team. Coming off the back of the double dissolution last election, we have a lot of the senate team up for re-election again. The ACT senate is also interesting and exciting, but a long shot, and we’re perpetually in the hunt for another lower house seat. But the focus is the senate.

“[In South Australia] Sarah Hanson-Young’s is a hard race. But Sarah is well known. Since the rolling of Turnbull, there is a whole pile of voters who said they would never vote Labor who are shocked and angry and looking for an alternative – the term that’s used is ‘unmoored’. They need someplace to go. And in SA you also have the absence of Xenophon now, so it’s become a whole lot more interesting with a lot of voters who are looking for a new home. So, we’re optimistic for a progressive senate but, with Palmer and One Nation in the mix, we’ll see.”

Adam Pulford, the Greens candidate for Wills, a contestable but long Labor-held seat in northern Melbourne, tells me he’s trying to arrest a sense among voters of a Labor victory being an inevitability. “What I say is simple: It’s a marginal seat and your vote matters. And second: We will support Labor’s good policies, but we will also challenge their bad.”

This week, senior Greens sources spoke of the “Turnbull factor”, described as the potentially beneficial revulsion of affluent, socially progressive Liberal voters with the removal of the previous prime minister. These voters, concerned with climate change and the Liberals’ seeming capitulation to hard-nosed conservatism, were angry, “unmoored” and liable to park their votes in unexpected places.

The Wentworth byelection, won last year by the independent Kerryn Phelps, was given as an obvious example, but hope was also found in the recent Victorian state election, where a swath of blue-ribbon seats fell to, or flirted with, Labor. Some Greens wonder if this new dynamic could benefit them, but the optimism is worth examining. Wentworth was won by an independent, not the Greens, and betting markets suggest the seat’s quick return to the Liberal Party. The recent elections in Victoria and New South Wales saw the Greens’ primary vote decline. How much federal politics influences state elections is both variable and debatable, but there is little electoral evidence that growing public concern with climate change – and increasing disgust with politics generally – has benefited the Greens much.

Kooyong, in Melbourne’s affluent east, is held by federal treasurer and Liberal deputy leader Josh Frydenberg. In its 120-year existence, the seat has always belonged to the Liberal Party or its predecessors – there have been few metropolitan seats in the country more favourable to the party.

But after Wentworth, the Greens began to wonder about the seat’s vulnerability. So did GetUp!, which conducted exploratory polling. The Greens’ optimism was confirmed in February this year, when the high-profile corporate and human rights lawyer Julian Burnside was announced as its new candidate for Kooyong. “I wouldn’t be here if I thought I couldn’t win,” Burnside said this week. “I’ve fought some really hard fights in my career, and I don’t like losing.”

Frydenberg’s challengers also include Oliver Yates, a former Liberal Party member, banker and chief executive of the Clean Energy Finance Corporation who is running as an independent. “The current Liberal Party have lost the plot,” he said in an opinion piece for Guardian Australia announcing his candidacy. “We have to change the way politics is done in Australia so we can address climate change, restore political integrity and ensure business operates within society’s expectations and not as an entity unto itself.”

Burnside and Yates have raised the profile of an electoral contest that in past years attracted scant attention. Internal polling also suggests Burnside has increased the Greens’ chances – though they remain slim – and his candidacy has energised local party volunteers.

But Burnside’s appointment was not without internal anguish and controversy. A year earlier, Helen McLeod, a former actuary, was preselected by local members as the Greens candidate for Kooyong. McLeod had also been the Greens candidate in 2016, winning a not inconsiderable 19 per cent of the primary vote – equal to Labor’s share. She was widely commended to me by party members as modest, diplomatic and gracious. Following the string of parliamentarians disqualified under section 44 of the constitution, McLeod had also relinquished her British citizenship in order to secure her preselection for the candidacy.

The Greens has long prided itself on what the party calls “participatory democracy” – the empowerment of its grassroots membership, and its ability to select local candidates. The process governing the replacement of candidates is clear: they can only be replaced if they’re found guilty of misconduct, or if they resign. In Kooyong, that process was followed – McLeod resigned and the branch endorsed Burnside. But many believed this occurred only after pressure had been applied – technically, local members had the right to retain their candidate but to do so would be a messy defiance of the will of party office holders.

Others saw an unsatisfactory recognition of McLeod’s work – work that was forgotten once Phelps’s victory in Wentworth excited the Greens to the benefits of a high-profile candidate. In conversations I had this week, no one doubted the electoral virtues of Burnside, but many were disgruntled that he had never been a party member before and seemed indifferent to the fact he had replaced a female candidate in a party that champions gender equity. “Women generally don’t react well to working away for years, invisibly, and then as soon as it gets towards the end some man bursts in to grab the spotlight,” someone close to the process told me. “Julian is a better candidate. No one has disputed this. If he had come a year earlier, this would never have been an issue.”

Hackles were raised again when, in a panel discussion on Sky News in March, Burnside admitted to his membership of the Savage Club – an elite social club open to only men. The QC quickly relinquished his membership.

“I’m disappointed to hear that,” Burnside says, when I raise members’ concerns. “[The preselection process] seemed pretty orthodox. It was my first direct involvement in Greens practicalities. I hadn’t been through the process before. I should say that I’m sorry if it’s caused hurt feelings. I’ve never met or spoken to Helen. Her husband seemed perfectly fine when I bumped into him. But I regret if anyone feels unfairly usurped. If people are cheesed off, then I’m very sorry.”

The late preselection of Burnside animates large and unresolved tensions in the Greens. How negotiable is the commitment to grassroots engagement? When does it begin to interfere with electoral competitiveness? Can a parliamentary party survive without the efficiencies of centralised decision-making? And how much pragmatism is allowed before it corrupts foundational values?

As a senior Greens source told me: “Kooyong is one of those perfect storm situations, where the Greens are an integral part of a serious effort to knock off the Liberal treasurer…

“The Kooyong campaign is a dark-horse, it’s truly extraordinary and we are very grateful that the Boroondara branch, who are all really solid, effective campaigners that have done a lot of incredible groundwork over many years, were willing to consider a change under these circumstances. The team there, including Helen, handled this with maturity and in the spirit of consensus, which is what we always strive for.”

This might be an understatement. Unlike the Melbourne seats of Northcote and Cooper (previously Batman), where Greens preselection contests bitterly degenerated into public feuds and sabotage, the Boroondara branch peaceably cohered around Burnside – although The Saturday Paper understands that this was achieved through great effort.

“I’m proud of the work we’ve done as a political party,” one Greens source told me. “But we’re immature in that we have yet to figure out how to win elections and find consensus and respect local membership. It’s a sort of administrative immaturity. This isn’t wicked or malicious. It’s just what comes when you have members, a lot who come from activism, and then you have staffers or organisers that have different approaches. We should be winning seats, but we say that the process is as important as the outcomes. Nationally, that’s hard to reconcile. I don’t know if we’ve figured that out yet.”