It is very difficult to imagine Mr Shaw being beaten - a sitting MP and in his second term as a Cabinet minister, he should, one would imagine, carry too much heft for his novice opponent.
That said, it can be perilous trying to gauge the mood of the Green Party membership, a disparate ensemble which comes to politics from a multiplicity of perspectives.
There is also precedent for a Green male co-leader not being an MP, Russel Norman being elected in 2006 but not becoming an MP until 2008.
As perhaps befits a party built on a foundation of activism, there is a longstanding tension between the party establishment and a solid section of its base.
Those rumblings resumed during last year’s election campaign when it, briefly, looked as though the Greens were in danger of missing the 5% MMP threshold and a faction of the party tried to place several sitting MPs in unelectable positions on the party list.
Even though the ship was righted and the bar cleared by a margin, some Greens still question just what the party is achieving through its co-operation agreement with Labour.
Like Mr Cockle for instance, who describes that agreement as the Greens being "Labour’s little helper".
He harbours far greater ambitions: he wants the Greens to aspire to not only be a major party but to be the major party.
In the time of climate change emergency we now live in, Mr Cockle believes New Zealand is ready and waiting to elect a government dedicated to ecological regeneration and equality for all.
Get ready for a radical rethinking of how New Zealand functions should Mr Cockle become Prime Minister Cockle, including decommodification of basic human rights such as food, water, transport, communication and housing.
Mr Cockle has a variety of policies available in series of YouTube clips for the curious, although - ominously for his election chances - viewership slumps from 1176 for clip 1 to just 49 for the most recent clip "What is the difference between James C & James S?".
In many ways the distinctions between J1 and J2 matter little - how the public perceives any dissension within the Green ranks is the important issue.
Just as much as James Cockle, James Shaw would like to see an environmentally focused government storming the climate change ramparts - this is a debate about methods and mandates.
Much as the party might like ecological wisdom to be the winner on the day and an appropriate decision to be implemented, this debate will grind on behind the scenes for some time to come.
Follow the leader
Should Mr Cockle succeed in his attempt to co-lead the Green Party, he will be the second Dunedin person to reach such heady heights, Metiria Turei being the first.
The South has not been blessed with that many leaders since party politics began in New Zealand, although there have been some notable examples.
Naturally, Otago Daily Times founder and two-time prime minister Sir Julius Vogel tops any list, although he was based in the North Island by the time he became PM.
Sir Robert Stout was the MP for Dunedin East when he twice became PM in 1884, his first government only lasting two weeks before losing a vote of no confidence.
Dipton farmer and former National prime minister Bill English is the most recent southerner to reach the political apex, while National’s first leader Adam Hamilton was a Southland grain merchant.
Two southerners represented New Zealand’s first organised political party, the Liberals, as prime minister: Thomas McKenzie and Joseph Ward - who would become premier a second time under the United Party banner in 1928.
Otago unionists Tom Paul and Jim Munro were prominent leaders in early incarnations of organisations which would eventually coalesce to become the Labour Party.
More obscurely, in the late 1960s Dunedin was briefly home to Gerard Williams’ Phoenix Party, and the NZ South Island Party rose and fell in Dunedin in 1999.