By Chris Mason
BBC Radio 4's Westminster Hour
Environmental issues have moved to the top of the political agenda
What's the best way for a political party - or indeed any organisation - to be led?
The Liberal Democrats appear to be faring better in the polls now, without a proper leader, than they did a few months ago with one.
And both Labour and the Conservatives - with great fanfare - have gone through the process of selecting new leaders in recent years.
Amidst all this, the Green Party in England and Wales bucks the trend. Or at least it has until now.
Falling in line
At the moment the Greens have two so-called principal speakers. As recently as 1991 they had six. Under the current arrangements, one has to be a man, the other a woman.
But the party's 7,000 or so members are being asked whether they should fall into line with the other parties and elect one person to be in charge.
As I've been finding out, the debate within the party is passionate and is exposing deep divisions over how the Greens should run their affairs.
Derek Wall, the male principal speaker, is arguably the most prominent member of the Green Empowerment Campaign, which is against having a single leader.
Caroline Lucas, a Euro MP and the female principal speaker, is a leading voice in the Yes to Green Leadership Campaign.
The foot soldiers in both camps, attempting to persuade, cajole and convince their colleagues to vote for them, are passionate about their cause - and irritated by their opponents.
I met Jenny Kemp, a former chairwoman of the Green Party, in her home village of Headcorn in Kent. She helps run the village Sustainability Group and a not-for-profit shop, selling local produce, called Una's Barn.
Not many food miles are clocked up here - and there is a chance to refill those shampoo bottles when they are empty, so as not to waste the carton.
To Jenny, keeping the party's current leadership is a matter of principle and philosophy.
She quotes to me one of the party's founding statements: "We reject the hierarchical structure of leaders and followers and instead advocate participatory politics, for this reason alone the Green Party alone does not have an individual leader."
To her, this is "such a powerful statement".
"If we want to make the changes in society that we need to make to bring about green politics, we actually need to stick to those basic core principles, we need to win over people's hearts and minds."
Caroline Lucas and Derek Wall are the party's principal speakers
To Jonathan Porritt though, former chairman of the party, that is rubbish.
"The idea there is some philosophical compulsion that we mustn't have a leader has always struck me as fantastical and part and parcel of some pretty deeply rooted naivety in the Green Party."
To him, the central justification for having just one leader is to ensure the party gets a fair crack of the media whip - at a time when environmental issues are at the top of the political agenda.
"There are lots of people in the Green Party who curl their lip at the idea of doing anything in order to make life slightly easier for the media," he says.
"It is not enough, apparently, to have to transform the entire world so we can all learn to live sustainably, they also want to take on the challenge of transforming the media.
"I think setting out to transform the way the media does work is just completely stupid. To take an idealistic view that says we are not going to play the media game, is like writing your own political suicide note."
But Jenny Kemp argues playing the media game - and having a single leader - is not just wrong in principle, but likely to backfire in practice.
She points to the recent fate of the former Liberal Democrat leader Sir Menzies Campbell.
"The media obsessed with his age and with the colour of his socks - and not with the policies of the Liberal Democrats.
"It seems to me it's not about image, it's about the political process, how we change politically to the sort of society we want."
The result of the Green referendum is expected on Friday or this weekend - and while those calling for change claim polling evidence suggests the public supports them - they need to secure a two thirds majority to allow it to happen.
It is thought the poll has provoked the highest postal vote turnout there has ever been for an election or referendum within the Green Party - already it appears around half the party have voted, with a few days still left for ballots to arrive at party headquarters.
So who is going to win? Those against any change say it is impossible to tell how members are voting. The Green Yes campaign say it is "nailbitingly close".