Mr Key says Sir Roger would not be in any cabinet of his, and Miss Clark is fighting hard to stop Mr Key having any cabinet at all. Her campaign adopts John Howard's 2004 winning theme of trust. Advertisements tell voters to trust her "strong and proven leadership" in an economic crisis, and promise to keep state assets.

A negative campaign paints National as risky. But after nine years, she has to defend allegations of creating a "nanny state".

Her social reforms, such as civil unions for gay couples, and increased government - a new state-owned bank, renationalised rail network, and an emissions trading scheme - are popular with her base, but sources of discontent among economic liberals and social conservatives.

Miss Clark has formidable experience in negotiating post-election support, and her best hope may be to stitch together enough support among the minor parties of the left.

All four polls have Miss Clark still falling short, but a stronger showing by the centre-left would make the Maori Party kingmaker.

It holds four of seven seats designated for Maori and the party pledges to deal with whoever offers the most to its constituents.

But a failure by Labour to close the two-year gap in the polls means the election remains Mr Key's to lose.

His campaign concentrated on the economy and improving New Zealand's fading lot compared with other rich countries, although the message is sometimes clouded by clunky language, like promising to "reincentivise New Zealanders with lower taxes".

He says while the environment is "on the page", it's not at the top.

Before the election was called, Mr Key said National could deal with the Maori Party, and this week he indicated his party's plan to abolish the Maori seats was negotiable (the Maori Party wants them made safer).

He has, however, ruled out negotiating with the suspended foreign minister Winston Peters. The pin-up boy for the blue-rinse set has been beset by donations controversies, causing Miss Clark to stand him down before the campaign. This week, he denied demanding the use of a helicopter from a donor with interests in government-controlled fisheries during an earlier campaign.

"Do you recall me flying around in helicopters in any campaign?" he asked on Television New Zealand. "Which politician worldwide would campaign from a helicopter? Don't be so stupid." Unfortunately for Mr Peters, he had. The Dominion-Post published a photograph of him preparing to board a helicopter during the 1999 campaign, and reported its journalist had joined him in another in 2005.

Few write off a politician as wily as Mr Peters, but his nationalist New Zealand First is polling about 3 per cent and he looks likely to be evicted from politics. That would give fewer options to Miss Clark, and boost Mr Key.