So why would Kiwis? Because Christmas it will most assuredly be if National's promised referendum on ' />

Turkeys don't vote for an early Christmas.

So why would Kiwis? Because Christmas it will most assuredly be if National's promised referendum on the electoral system sees the ditching of MMP.

Christmas, that is, for the two major parties.

No longer shackled by coalitions or minority government, National and Labour will struggle to suppress their glee at being gifted a return to the good old days (for them) of first-past-the-post (FPP) revolving-door elected dictatorships.

And before anyone mouths the words "supplementary member", let's beware of false prophets in sheep's clothing.

No doubt those wanting a return to those dark ages will seductively offer the supplementary member system as a halfway house between FPP and MMP. That system is in part proportional. It might look like a compromise. It is not. It is nothing short of snake oil elixir.

Had last year's election been fought under that system with a Parliament made up of 90 constituency seats and 30 list seats, National would have won 67 of them, compared with its current 58.

That party would have had an absolute majority of 14 seats with just under 45 per cent of the vote. The Greens' current entitlement of nine seats, would have been slashed to just two. So much for proportionality.

Worse, if voters give MMP the boot, they will have chucked away the only means by which they can curb the power of the Executive, if only in a blunt and roundabout fashion. How stupid is that? Yet, opinion polls consistently show FPP will give MMP a serious run for its money.

Tossing MMP would be slightly defensible (though still utterly inexcusable) if voting for an alternative guaranteed some meaningful reform of Parliament's practices and limits on the powers of the Cabinet.

But it won't happen. National is not offering such a quid pro quo. It should. But why would it if it can get away with not doing so?

The debate is already being framed as an "either/or" choice. The country voted in 1993 to switch from majority FPP to the fully proportional mixed-member system. So what is wrong with simply switching back?

Everything. In case anyone has forgotten, Labour's and then National's railroading of hugely unpopular reforms through Parliament left angry voters no option but to fight for an electoral system that slowed things down by making it highly unlikely those parties could rule alone.

Losing MMP would be a giant leap backwards; a constitutional tragedy of disempowerment given the gaping absence of limits on Cabinet power in a unicameral Parliament.

If big business wants rid of MMP, fine. But it must explain why New Zealand's democracy should not enjoy the safeguards other Westminster-style democracies do. The business elites might say how they intend to remedy this democratic deficit in the absence of the politicians doing so.

A full and proper referendum debate would canvas how Parliament could be improved - for example, by picking up the Greens' ideas like reform of the Official Information Act, registration of lobbyists and a fixed election date.

Instead, the country is drifting towards another constitutional change made in isolation, principally because National feels obligated to fulfil an election promise that some of its newer and younger MPs now probably wish it had never made.

The Prime Minister says, without much enthusiasm, it is time to "kick MMP's tyres". Maybe. But does that require dismantling the truck?

MMP has worked. It has not been found wanting. It has delivered when an emergency has required swift action. Witness the co-operation over the bank deposit guarantee scheme.

MMP has produced a Parliament that is far more representative of society - and more responsive to a diverse society's needs.

MMP has not spawned a plethora of small parties rendering the country ungovernable - the so-called Italian disease. Despite some unwieldly-looking arrangements, stability has never been an issue.

The number of parties in Parliament is actually on the decline as politicians who rebelled against the cloying caucus discipline of FPP politics - Winston Peters, Jim Anderton and Peter Dunne - start to exit the political stage.

The tail has wagged the dog far more rarely than anyone envisaged. Instead, the dog has eaten the tail. Minor parties have paid a heavy price for propping up governments.

Crucially, whatever the result on election night, it has been clear immediately who can and cannot govern - even in 1996 when there were two viable options.

Above all, the system is fair. What it has done in a conservative-minded country is make it more difficult for the conservative party to win power.

A bias existed under FPP because Labour votes are concentrated in cities while National's support is spread more evenly geographically.

Presumably that is why opposition to MMP is much stronger in provincial and rural areas. What is not in question is that the loss of that bias is the unstated, but underlying reason National has kept promising a referendum.

All this is not to say there is nothing wrong with MMP. That is where attention should focus. There is no justification for the rule which removes the 5 per cent threshold if a party wins a single constituency seat. That Act with a smaller party vote than NZ First ended up with five MPs and NZ First with none is patently unfair.

Harder to deal with is defeated constituency MPs seeking sanctuary in the list as a way back to Parliament. That really annoys voters. As did the failure to hold a referendum after two MMP elections.

No such promise was made, however. What was promised was a select committee review. That happened. It did nothing. Disgruntlement has bubbled away since.

National's resulting promise of a referendum was made to compensate for John Key's "me too" politics of making policy compromises to thwart Labour in the centre-ground. Key needed a bone to feed those to his right.

Key will not campaign for a change. To do so would jar with his success in making MMP work for National, particularly in relation to the Maori Party.

The latter will not be worried by the referendum. Its agreement with National specifically puts the Maori seats off-limits as far as that plebiscite is concerned.

Given National cannot fulfil its promise to abolish those seats, however, MMP has been thrust into the role of substitute whipping-boy for National supporters who think the party has sold out to Maori.

It all adds up to easy, populist and self-serving politics. National cannot lose because any change of electoral system will be to one less proportional than the current one.

But getting there will not be cost-free. The Government will have to manage the referendum process. Key will not be able to divorce himself from that. No matter how it goes about formulating the referendum's wording and options, National will be accused of trying to manipulate the result. It is all going to be more complicated and messy than National thinks.

But as the saying goes, as you sow so shall you reap.