Key announced a week later that he would lead a National minority government with confidence-and-supply support from the ACT, United Future and Māori parties.

The Constitution Act 1986 defines the term of Parliament as "three years from the day fixed for the return of the writs issued for the last preceding general election of members of the House of Representatives, and no longer".

Political scientist Stephen Levine from Victoria University speculated that the low turnout may have resulted from the National Party's large lead over Labour in opinion polls running up to the election.

[11] Economic downturn has led to high-profile job losses, such as the closure of factories in Foxton,[12] in west Dunedin[13] and in southern Hawke's Bay.

[14] At the same time, inflation hit an eighteen-year high,[15] with an upwards tug on the prices of basics such as food and petrol, the latter crossing the two-dollar-per-litre mark in late May.

[18] Also signed up to the plan was the National Party, with deputy leader and finance spokesperson Bill English saying that there was "still time to change the...scheme if banks find it hard to borrow overseas".

[21][22] John Key responded to the news by describing the numbers as "a bit worse than we had anticipated", and stated "I'm confident we can deliver a programme of tax cuts.

[26] On 9 October, National released its policy, promising people on the average wage or higher around $47 a week extra in the hand, funded through a combination of cutting contributions to KiwiSaver, eliminating a tax credit for science and development, and changing Working For Families entitlements.

[28] Members of the Labour Party accused John Key of lying about his shareholding in Tranz Rail, by not disclosing nearly half of the shares he and his family trusts owned in the company, even though this presented a clear conflict of interest with Key's role as his party's spokesperson on transport, at a time when he asked several questions in the House about the government's plans regarding rail infrastructure.

On 22 September, the committee determined that Peters had "provided misleading information" and recommended he be censured;[30] this was done by the House of Representatives in a 62–56 vote two days later.

The new seat, originally dubbed "Howick" (after the Auckland suburb), would have included parts of the existing Pakuranga, Manukau East and Clevedon electorates.

The swing to National in the central North Island saw two Bay of Plenty seats produce close results: in Rotorua, the sitting Labour MP Steve Chadwick prevailed by just 662 votes (2.17%) over National's Gil Stehbens, and in Tauranga, property developer Bob Clarkson defeated New Zealand First's leader and seven-term MP for Tauranga Winston Peters by 730 votes (2.02%).

Besides the three Labour-held narrow-margin seats mentioned above (Otaki, Hamilton West and Rotorua), National had prospects of gaining Taupō, where boundary changes have added the National-leaning town of Cambridge and with it nearly 20,000 different voters – putting sitting MP Mark Burton's 2005 majority of just 1,285 votes (4.43%) at risk.

Māori Affairs Minister Parekura Horomia also held on by a small margin against veteran broadcaster Derek Fox in Ikaroa-Rāwhiti.

Incumbent Mahara Okeroa, however, was defeated by Rahui Katene in Te Tai Tonga, giving the Māori Party an additional seat.

Polling for a preferred Prime Minister showed Helen Clark nearly twice as popular as then National Party leader Don Brash.

Things changed in early 2007, with new National leader John Key improving on Brash's preferred Prime Minister rating by ten points, and overtaking Clark as preferred Prime Minister in May; at the same time National jumped out to a sizeable lead over Labour ranging from between eight and eighteen points, spending most of 2007 and 2008 with support from around fifty percent of the electorate.

Labour's popularity slumped, hitting its lowest point in the winter of 2008, before beginning a slow climb into the high thirties in August and September.

[37] The Progressive Party, led by Jim Anderton, had served as a steady coalition partner to Labour and the electorate probably expected it to remain so.

[38] In the light of New Zealand First's run-in with the Serious Fraud Office, John Key ruled out that party as a government support partner on 31 August 2008, saying "the sheer weight of allegations and the actions of Mr Peters in the last few months means that I have lost that confidence in him".

[39] At that time, Peters' future seemed under a cloud; after his party being cleared of charges of serious fraud, National restated its position, saying that the result of the case has not altered it.