Even those well-acquainted with the acrimonious, schismatic and unforgiving atmosphere which turn contests on the far left of politics into messy battles - mixing ideological machination with personal recrimination - would have been stunned by Sue Bradford's venomous vilification of the Greens earlier this week.
Without any prompting, New Zealand's irrepressible Icon of the Class Struggle volunteered the truly mind-boggling assertion that the Greens had sold out on their so-called principles and had executed a complete ideological U-turn such that they had now "nailed their flag to the mast of neo-liberal capitalism".
It was akin to alleging the Pope was about to revive the slave trade of previous centuries and profit from it by setting up a private consortium with himself and the Devil as joint shareholders.
Bradford went so far over the top in a Radio NZ interview that she was not so much off the planet as way beyond the boundaries of the Milky Way.
Source: 1 NEWS
Bradford's feet are firmly grounded in this world, however.
When she speaks, she does so not merely to pass the time of day.
She always has a point to make. In rounding on the party which she represented in Parliament for nigh on a decade, she had a very big point to make.
Bradford was aghast that the Greens have forged an agreement with Labour which sets the parameters within which the two would-be coalition partners will manage the government finances should they have the numbers to rule after September's election.
We are talking big things here. Things like tax rates, government spending, Budget surpluses and debt repayments.
The aforementioned parameters will be determined by a list of "Budget Responsibility Rules".
While the Greens will still be able to make all the manifesto promises they wish during an election campaign, they will find themselves strapped in a straitjacket afterwards.
The coalition's fiscal policy will instead match the senior partner's far more cautious approach.
The Establishment might not technically be in power. But Bradford's experience of her long-time crusade to stop the unelected from using their positions of privilege to exercise power behind the scenes will be telling her that the Establishment will be saddling up Fiscal Responsibility as a Trojan Horse which will deliver Fiscal Conservatism.
The Greens may end up being mere spectators to this event. But tighter limits on spending than the Greens might have been envisioning might jeopardise their plan to mount a major onslaught on child poverty.
Bradford argues such scenarios all add up to a likelihood that the Greens will not only sell out on principles. They will sell out on their promise to make the lives of the poor and downtrodden significantly better.
The Greens are handicapped by something else. During Bradford's era in Parliament, the Greens' not-so-secret mission was to supplant Labour as the dominant centre-left party.
They failed to do so. Voter support for the Greens appears to have plateaued at around 10 per cent - far short of Labour's current rating at around 30 per cent.
The Greens' priorities have consequently shifted. They are now far more willing to make concessions to political realities in order to get into government in some shape or other.
Labour is no longer the enemy. National is.
If they are serious about wanting to govern, the Greens must help Labour get a very large monkey off their backs, namely National's unceasing efforts to typecast them as chronic "tax, borrow and spend" parties.
The Budget Responsibility Rules are designed to provide meaningful rebuttal. They require a Labour-Greens coalition to consistently run surpluses, pay back debt, limit government spending to a certain percentage of gross domestic product and resume contributions to the Cullen super fund.
It all sounds very much like the National Party in drag.
The politics are shrewd, however.
For example, when it comes to ensuring the coalition partners take a "prudent" approach to Government spending, the new rules note that during the global financial crisis, core spending rose to 34 per cent of gross domestic product.
That figure has since fallen to around 30 per cent of GDP "and we will manage our expenditure carefully to continue this trend". Absent is any mention of the Treasury's forecast that on current settings that figure will fall to below 28 per cent.
When it comes to having more money to dish out, Labour and the Greens should be grateful that bumper Budget surpluses are very much on the short-term horizon thanks to the expectation that economic growth will remain rosy.
Were the Government's books in deficit - and projected to remain so - negotiating a credible and lasting agreement covering the operation of the Government's fiscal levers would have been a very different and very difficult proposition.
If the Greens have any reason to feel they have been stitched up by Labour, it is on tax policy.
Andrew Little has already ruled out raising taxes. The Greens' hopes of getting the introduction of a capital gains tax on the Cabinet agenda will hinge on the recommendations of yet another panel of tax experts.
The release of the Budget Responsibility Rules amounts to another significant pre-election milestone in demonstrating Labour and the Greens are fit for purpose when it comes to governing.
Given voters' prejudices - especially the deep-seated antipathy many feel towards the Greens - the biggest question of all is whether it is all happening too late to have a major impact on September's ballot.