Having turned its caucus room in Parliament Buildings into a war room staffed almost around the clock by policy wonks, political strategists, experts in social media, plus assorted press secretaries - all in readiness for the coming general election - the Labour Party may find itself with another war on its hands before then. Or something close to it.
The "enemy" on this occasion will not be National. Neither will it be Act. Nor United Future. Nor Colin Craig's Conservatives. Nor even Kim Dotcom and his Internet Party.
No, this war will be of the internecine variety where the combatants all come from the same neck of the (political) woods.
It will have been sparked by the seemingly endless positioning and posturing ahead of September's election which will count for little in the aftermath. But this week it all turned ugly for the Greens. And things may yet get uglier still.
It may be that fate has decreed that the power struggle between Labour and the Greens takes centre stage at the worst possible time for the centre-left.
It may not come to open warfare. But the dismissive, almost contemptuous attitude displayed by David Cunliffe with regard to a supposed ally is bound to rankle deeply wherever Green Party members gather.
You can be assured there will be a response; that there will no longer be any scruples about upstaging Labour on the hustings.
The Greens will, however, not want to get into a prolonged spat which damages them as much as Labour in the run-in to polling day. The Greens may well wait until after the election when Cunliffe will need them on board in some form or other should he be in a position to cobble a government together.
The Greens may put the stress on peace, love and understanding in the resolution of disputes. Their image may be more flower power than firepower.
But the closer the party gets to seats around the Cabinet table - and thus the exercising of real power and influence - the more the Greens are toughening up to cope with the pressures of being a coalition partner. They simply have to do so. And this week showed why.
Russel Norman, in particular, has shifted into a higher gear in terms of tenacity in both promoting and defending his party. He is now de facto leader rather than just co-leader. He grabs people's attention. And they listen. The same cannot be said for Labour's leader.
The Greens have been exceptionally patient with Labour in expectation that a centre-left victory in September will finally bring long-delayed reward.
They are acutely conscious, however, that time is running out and Labour has done precious little to fill the empty canvas on the centre-left which is Labour's failure to paint a picture in voters' minds as to how a Labour-Greens government would function and what its priorities would be.
Such information is crucial in building voters' confidence that they will get what they think they are getting - as well as being an antidote to John Key scaring voters off Labour by reminding them of the Greens' supposed whackiness.
Labour's failure to take the initiative must have made the Greens suspicious. So they approached Labour with a proposal for both parties to co-operate to a much greater extent in the run-up to the election and "brand" themselves as the Government-in-waiting.
What the Greens were really doing was testing the extent of Labour's commitment to working with them in government following signs that Cunliffe was wavering on that question.
The Greens got their answer soon enough. It was not what they wanted to hear. They got a lecture in semantics - that the next Government would be a "Labour-led" one, not a "Labour-Greens coalition" - and a lesson in history - that Labour had been the dominant party on the centre-left for the past 100 years and thus called the shots as of right.
Cunliffe made it patently clear in word - and more so in tone - that Labour was decoupling itself from the Greens and would be seeking to "maximise its share of the vote" - code for saying it was now open season on territory occupied by the Greens.
Neither could Cunliffe muster much enthusiasm when asked to digress on how Labour would treat the Greens in any post-election negotiations.
Of course, Cunliffe's remarks were for targeted at an audience of one - Winston Peters. Cunliffe knows he will likely need both New Zealand First and the Greens to make it to the swearing-in of a new Government. But it is Peters' chalk to the Greens' cheese. It is Cunliffe's conundrum.
Peters has choices. The quickest way to have him running helter-skelter towards National's camp would be for Labour to get tied down in some pre-election arrangement with the Greens.
The Greens are consequently expendable. But for how long? Cunliffe is clearly taking things step-by-step, conscious that the voters might solve his problem. Or compound it.
But Labour's antipathy cuts deep. Labour does not trust the Greens and believes that party is seeking to supplant it.
Labour desperately needs to lift its poll ratings otherwise Cunliffe's claims of Labour's historic superiority will sound increasingly hollow.
And Cunliffe is personally under huge pressure to increase Labour's share of the vote which (embarrassingly for him) has fallen below the levels achieved by David Shearer during his tenure.
The centre-left parties need to expand their shared of the overall vote to worry Key - rather than cannibalising one another's existing holdings.
The net result of this week's wrangling is to reduce the centre-left's share even more. The message most voters would have picked up is that Labour no longer wanted to work with the Greens. Voters hate disunity and punish accordingly.
The Greens deserved better. They are not responsible for Peters' existence. Cunliffe could have been less dismissive and more accommodating in his language.
He could have accepted a much more limited pre-election understanding. Something symbolic, like Jim Anderton's invitation to Helen Clark to speak at the Alliance's conference a year before the 1999 election.
Key likes to wind Peters up; Cunliffe risks looking like he is being cowered by the veteran politician.
Labour's pursuit of power dictates, however, that Labour be hostage to Peters for the next five months despite knowing such obedience will not make even the tiniest bit of difference as to whether he ultimately favours the centre-right or centre-left.
How that squares with Labour's proud history is something Cunliffe might like to explain. Or, more likely, might not.