New Zealand will hold one of its triennial national elections tomorrow, and all the polls suggest the ruling conservative National Party stands on the cusp of an extraordinary achievement: a parliamentary majority achieved under a proportional representation voting system. The final poll from New Zealand Herald-Digipoll has the National Party on 50.9 per cent, while Roy Morgan (a phone poll of 959 respondents) has it at 49.5 per cent. The opposition Labour Party on the other hand is languishing on 28.0 per cent and 23.5 per cent respectively. The National Party is nonetheless a few points off its peaks from earlier in the campaign, and intricacies of the electoral system mean a simple majority of the vote might not be enough to translate into a majority of seats. But with two minor parties including the substantial Act New Zealand committed to support a National Party government, Prime Minister John Key’s hold on office looks secure in any case.
Under the mixed-member proportional system, voters are given a “party vote” as well as voting in first-past-the-post elections for 70 constituency seats. It is the party vote which is of interest to casual observers, as it ultimately determines the partisan composition of the parliament. In addition to the constituency members, 50 “top-up” seats are allocated in such a way as to give each party a share of seats more-or-less proportional to its share of the vote – provided they either clear a 5 per cent threshold of the national vote or win a constituency seat. The other peculiarity of the New Zealand electoral is the seven single-member Maori electoral districts: voters opt to be on either the Maori or the general roll, and exercise their constituency vote accordingly.
For the latter reason, the only constituency seats of interest to non-local observers are those which might be won by minor party candidates whose parties poll less than 5 per cent nationally. Success will entitle them to between zero and five extra seats, depending on the size of their party vote. Barring surprises, the only two seats which appear to fit the bill are Epsom, held by Rodney Hide of free-market liberal Act New Zealand, and Ohariu, held by Peter Dunne of the religious-cum-centrist United Future New Zealand. Act New Zealand currently has five seats in parliament on the back of its 3.6 per cent party vote in 2008, which would have been zero if Hide had lost his seat – although he in fact won very easily. Dunne on the other hand retained Ohariu narrowly, and United Future did not score enough party votes to win further seats. The 2008 election also saw the parliamentary demise of the once-prosperous New Zealand First party after its leader Winston Peters lost his seat of Tauranga, and it fell below the threshold in the party vote. However, the polls suggest it has undergone a surprising (to me at least) revival: their support is at 5.2 per cent from Digipoll and 6.5 per cent from Roy Morgan. Peters is top of the party’s list, and is not contesting a constituency seat.
The other operative minor parties are the Green Party, the Maori Party and, to a lesser extent, the Mana Party, a breakaway from the Maori Party formed when Hone Harawira resigned from it (New Zealand electoral law then obliged him to face a by-election in the seat – his success presumably stands him in good stead to retain the seat tomorrow). The Green Party won the seat of Coromandel in 1999 but has otherwise relied on clearing the threshold to win representation. It had a struggle achieving this until its vote lifted to 6.7 per cent in 2008, and is expected to do substantially better this time, with polls consistently indicating a vote in double figures and a representation of at least 14 seats (although Australian experience suggests they might not meet such lofty expectations). The Maori parties make the outcome in the seven Maori seats relevant to the final party totals, giving the Maori Party in particular the opportunity win substantial representation without clearing the threshold. The party won five seats in 2008, one of which it lost with Harawira’s departure earlier this year, but this time it will be encumbered by vote-splitting with the Mana Party. The other two Maori seats are held by Labour.
As noted at the beginning, the peculiarities of the system can distort the proportional conversion of votes to seats. Firstly, the capacity of the Maori Party in particular to win more constituency seats than its party vote would entitle it to can result in an “overhang”, meaning a greater number of seats in parliament than the normal 120. Its five-seat haul caused this to happen for the first time after the 2008 election, boosting the total number of seats to 122. This affects the National Party’s chances of winning a majority as its share of the vote will only be converted into a share of the base 120 seats. Another theoretical possibility for an overhang is that the National Party will so completely dominate the constituency contests that it will emerge with more seats than its party vote share allows. To do so it would need to win as many of 60 out of the 70 seats. Without having investigated the situation too closely, this doesn’t seem to me to be entirely implausible in circumstances where one major party is so completely dominant in a single-member electoral contest (witness the New South Wales state election). Another point in the National Party’s favour is that they will benefit from the 5 per cent threshold, as votes for parties which fail to reach it will be excluded from the seat calculation – hence lowering the bar to obtain a majority of seats.
The other feature of tomorrow’s poll will be a non-binding referendum on the electoral system, with all indicators pointing towards the retention of mixed-member proportional. Voters will first be asked if they wish to keep MMP or change to another system, and then given four options to choose from if MMP is abolished. Two of these – first-past-the-post and Australian-style preferential voting – involve a complete reversion to a single-member constituency system and the abolition of proportional representation. A thirde, the Australian Senate-style single transferable vote, would do the opposite – constituencies would be abolished and all seats determined at national level (CORRECTION: Martin B in comments points out that the plan is to have 24 to 30 districts proportionally electing between three and seven members, giving minor parties much higher hurdles to clear – what is known in the trade as “low magnitude” PR). Finally there is the “supplementary member” system, which would be similar to MMP except that the party seats would simply be allocated according to the parties’ shares of the total vote, rather than being used to achieve an proportional result overall by “topping up” the constituency result. This would reduce the number of minor party MPs without eliminating them entirely, making majority government easier to achieve.
The supplementary member system is favoured by the National Party, but all other major players favour the status quo. The latter seem likely to get their way: the Digipoll referred to above finds 54.4 per cent planning to vote to keep MMP. On the second question, 29.9 per cent favour first-past-the-post, 17.2 per cent favour the single transferable vote, 13 per cent favour the supplementary member system, and only 11.4 per cent favour preferential voting. Much further reading from Antony Green, and also Charles Richardson at Crikey. I suppose it’s also possible that some actual New Zealanders have had something to say about the election, but here I reach the limits of my knowledge.