KEY POINTS:
Peter Dunne's warning that Labour cannot take United Future for granted initially sounded like sabre-rattling from someone with precious few sabres to rattle.
While smarting at the attention Labour is paying to the Greens at the expense of United Future, its formal partner, Mr Dunne quickly ruled out ripping up his party's confidence and supply agreement with Helen Clark before the next election.
That would not fell the minority Government, although it would give Labour even less room for manoeuvre on legislation than it has now.
United Future would be the big loser. Such a drastic step would relegate the two-MP party to the irrelevance currently enjoyed by Act and destroy its carefully nurtured image as a party that works constructively, rather than spitting the dummy when thwarted.
Mr Dunne is not usually prone to making empty threats, so the warning in a political stock-taking speech on Tuesday night was greeted with some puzzlement around Parliament.
Was this another tantrum along the lines of his bad-tempered joust with the media on election night in 2005 after watching his party's House representation sliced in half?
What he was really telling Labour was that if it wants United Future's help to form the next Government, it had better start showing some loyalty to its support partner now rather than letting its eyes drift towards the Greens, its natural ally.
National received a similar message for ignoring United Future and focusing instead on forging a relationship with the Maori Party.
It is after the election that Mr Dunne could exercise leverage if the numbers in Parliament fall to his advantage. He is essentially using the potential leverage he may have post-election to press both major parties to show some respect beforehand.
But United Future's very readiness to be a partner inevitably means Labour and National will continue to take it for granted. If they need him, they will ask themselves whether Mr Dunne wants to sit in Opposition for three years and assume he does not.
Mr Dunne is pigeonholed as the bride-in-waiting and never the bridesmaid - the role filled by the Greens at the past three elections.
Gordon Copeland's defection from United Future may explain why Labour's eyes are wandering. That has made it potentially harder for Labour to pass laws which do not have the Greens' backing. That party has more bargaining power. Mr Dunne has less.
Mr Dunne's unhappiness at being treated by Labour as "second class" springs from United Future having a confidence and supply agreement with Labour. That should see his party ahead of the Greens in the Beehive pecking order because the latter have a far looser co-operation arrangement.
United Future did not sacrifice some of its independence just to see Labour kowtowing to the Greens, who have managed to preserve theirs yet still extract major policy concessions.
That casts a different light on Mr Dunne's invitation to National to work on issues of common interest this side of the election while still being in a formal arrangement with Labour.
What looks like a radical innovation of MMP politics which is intended to convince voters National and United Future can work together after the next election also doubles as a means of punishing Labour.
United Future has another pressing reason to put some distance between itself and Labour.
Tuesday's speech may have been written before the rash of polls indicating National is soaring ahead. But if Labour has hit the iceberg, it is sensible to search for a lifeboat.
Peter Dunne
* MP 1984 - present
* Political affiliations: Labour Party 1972 - October 1994; Future New Zealand 1994 - June 1995; United New Zealand October 1996 - November 16, 2000; United Future New Zealand November 16, 2000 -
* Age 53
* Married, two sons
