Tensions and periodic tantrums are built into coalition politics, just as compromise and pragmatism are an essential part of a coalition leader's armoury.
Helen Clark grasped this early on in her prime ministership and turned it into an art form.
John Key and his Government, schooled in it during three terms in opposition, learned their lessons well.
Perhaps too well.
For now they are trumping the Labour Party.
The latest manifestation is the sudden - it has been described as "secret" - accession on Tuesday to the United Nations Declaration on the Rights of Indigenous Peoples with a statement delivered by Maori Party co-leader and Maori Affairs Minister Dr Pita Sharples to the United Nations in New York.
It has been met with tension, and what might be described as a tantrum, by the third party in the coalition Government's bed: Act New Zealand.
Leader Rodney Hide has responded to the news with a display seldom seen even within the somewhat elastic emotional parameters of coalition politics.
"The Act party believes that the declaration is divisive and will set New Zealand on a path to a further divided nation - separating New Zealand into two, rather than bringing us all together.
It is the very opposite of Act's policy of one law for all New Zealanders," Mr Hide said, adding that the party was "deeply disappointed that he [Mr Key] has failed to honour the `no surprises' policy set out in the Act-National Confidence and Supply Agreement".
In November 2005, the vitriol was coming from a different direction.
Still stinging from the passage of the Foreshore and Seabed Act, Maori Party co-leader Tariana Turia attacked the Clark government of the day for having gone to New York a month previously "and criticised the draft Declaration on the Rights of Indigenous People as being `unworkable and unacceptable'."
New Zealand declined, along with three other countries at that time including the United States and Australia, to participate in the declaration invoking, Mrs Turia claimed, distress among indigenous communities throughout the world at its actions.
The Clark government's rationale for its statement of opposition at the General Assembly back then was that New Zealand could not agree to a document suggesting there were two standards of citizenship, or two classes of citizen, when the Treaty of Waitangi existed, which, it argued, was signed so that two peoples could co-exist in one nation.
Article 26 of the UN declaration states that indigenous peoples have the right to own, use, develop or control lands and territories that they have customarily owned, occupied or used.
At the level of treaty claims, Labour's chief fear was that such a declaration was at odds with, and might be used against the processes already in place under the auspices of the Waitangi Tribunal.
So while principle ruled, it could also see practical difficulties were it to endorse the declaration.
The National Party leadership evidently anticipated some fallout from this week's decision.
The status of such a declaration, it points out, is neither that of a treaty nor a covenant, is legally non-binding, and is an "expression of aspiration".
Be that as it may, the statement delivered by Dr Sharples in support of the declaration acknowledged that "Maori hold a special status as tangata whenua, the indigenous people of New Zealand and have an interest in all policy and legislative matters".
This does not go quite so far as endorsing the ambition, expressed by Dr Sharples to Parliament in 2006, that "As Maori, our rangatiratanga is expressed in our rights to determine our own economic, social and cultural development ...
The Maori Party celebrates the right of self-determination" - but it comes perilously close to it.
Mr Key and senior National Party figures will be gambling that this gesture towards the Maori Party will further enhance the mana of the latter, cement more tightly the political allegiance between the two parties, and deflate the more demanding ambitions of radical Maori - personified in Parliament in the character and rhetoric of Hone Harawira - while, in practice, giving nothing at all away.
They appear to have decided that the subtlety of principle should be subjugated to the symbolic glue of pragmatism.
It may make political sense, but while National retreats to the safety of descriptors such as "aspirational" and "non-binding", it is hard to escape the conclusion that, on this matter, it speaks with a forked tongue.
