John Armstrong writes that of the five Governments formed since MMP, three have had minor-party meltdowns, and this Administration may suffer too.

The increasingly erratic and somewhat flaky behaviour of Act and the Maori Party should be giving the Prime Minister some serious cause for worry.

Running a minority Government is fraught at the best of times. In John Key's case, the omens point to it only becoming more so.

The Prime Minister might be tempted to replicate the maxim of one of his predecessors. When she woke up each morning, Jenny Shipley's first thought, figuratively speaking, was to count the numbers to make sure she still had a minority government to run.

With Key's Administration, however, stability has not been something in question. Even if there was some crisis which destabilised the current governing arrangement, National would be unlikely to lose its majority on confidence motions.

Were Act to disintegrate, its MPs would still almost certainly back National as independents.

Above that bottom line, however, there is ample room for things to get incredibly messy, especially in getting legislation through Parliament.

Act is now paralysed by a very public fight over its direction and who should be its leader. The trouble is that the differing factions have reached a stalemate - a dreadful outcome which leaves the party stuck in limbo going neither forwards nor backwards.

To Key's left is the Maori Party, which is feeling increasingly hassled about its relationship with National and, as a result, increasingly bolshie.

History offers Key no comfort. Of the five governments formed since the introduction of MMP, three have experienced minor-party meltdowns. There is no reason Key's Government should be exempt, especially as it has yet to reach the halfway stage of its three-year term and trouble is already brewing.

Looking at the dynamics within Act and the Maori Party, you would not put a lot of money on either party making it to next year's election in the same shape as they came out of the last one.

In Act's case, once last year's attempted putsch against Rodney Hide had failed, it would have been assumed that the party's parliamentary wing would have closed ranks and made the standard, empty-sounding vows of unity.

There has been nothing of the sort - quite the opposite, in fact. Witness the cutting remarks, the oblique responses to questions and the ugly body language displayed by Hide and his deputy Heather Roy towards one another on TV3's The Nation last weekend.

Roy and her ally, Sir Roger Douglas, argue Act must forge a new path which takes it out of National's shadow and re-establishes the party's independence and differentiation. Doing this, they say, would see Act boosting its share of the party vote well above the 5 per cent threshold and (conveniently) no longer reliant on Hide's Epsom seat as a parliamentary lifeline.

Hide, however, relentlessly preaches that Act's priority is to provide stability to a centre-right Government and everything else - be it the Auckland Super City reform or the three-strikes policy - flows from that.

Hide holds the upper hand because, first, he holds Epsom and thus controls Act's parliamentary lifeline, and, second, there are serious doubts that the Roy-Douglas strategy is capable of working in the relatively short time left before next year's election.

The evidence for saying that lies in Act's failure to fill the gap in the centre-right market opened up by Key's cautious, middle-of-the-road approach to governing.

Act cannot capitalise because its current ideological stance has become deeply unattractive to the very people to whom it should be appealing.

As former Act MP Deborah Coddington has noted, Act's morally conservative stance on things like smacking and its hard line approach to law and order are anathema to urban-based liberals who might be attracted by Act's more market, less government agenda.

Likewise those who might find Act's brand of social conservatism appealing are pathologically averse to the party's radical economic prescription.

It's lose-lose. The contradiction is reflected in the make-up of the Act caucus which leaves Hide having to bridge the divide between economic liberals like Sir Roger and social reactionaries like David Garrett.

It is little wonder there have been ructions. But straightening things out will only cause more ructions, thus further damaging Act in the eyes of the public. Hence the uneasy stalemate.

There is little that the Prime Minister can do to help beyond what he has done already by repositioning National more to the centre.

The Maori Party's plight is a different, but simpler case. Even parties with similar ideological leanings have difficulty co-habiting in Government. What chance two parties from disparate parts of the political spectrum managing to do so?

The Maori Party's last-minute withdrawal of support on Wednesday night for Government legislation which replaces Environment Canterbury's councillors with commissioners may have irked National. But such behaviour is a sign that the pressure is starting to tell on Tariana Turia and her colleagues.

In particular, the minister-outside the Cabinet arrangement which worked so well for Peter Dunne and Winston Peters may not be helping the Maori Party. At times, it seems as if Turia and Pita Sharples, the party's two ministers, are in coalition with National rather than a more distanced support arrangement. Ironically, had the Maori Party been in coalition, it could have - as Jim Anderton pointed out - invoked the agree-to-disagree clause in the Cabinet Manual and voted against National's welfare reform package.

Turia instead felt obliged to vote for it on the grounds of Cabinet collective responsibility because she is bound to uphold Government policy in her Social Development portfolio.

The Maori Party has already had to swallow a lot of things it would prefer not to digest - National's emissions trading system, for example. With National picking up the pace on economic reform, the diet will become even less appetising.

The squeals of pain from the Maori Party are consequently becoming louder and more frequent, be it Sharples on national standards or Turia's attempt to divert attention away from National's welfare measures by claiming she had not been consulted.

Still to come are National's tax cuts which will benefit top income-earners the most. To top things off, National's plan for resolving the argument over the foreshore and seabed has landed smack bang in the middle of all this.

Suddenly, the Maori Party is being asked some big questions about where it stands and who it stands for.

Hone Harawira may well describe Attorney-General Chris Finlayson's compromise on the foreshore and seabed as "dumb". But Harawira will have to swallow the compromise or otherwise accept that the foreshore and seabed will stay in Crown ownership. Or leave the Maori Party. Big questions demand big decisions.

The next couple of months will be the sternest test yet of his willingness to stick around. But he will not be the only one having to think very hard.

This period stacks up as the toughest test yet of whether the wider Maori Party's relationship with National can endure.