KEY POINTS:
Electorate races have faded in importance under MMP, but a handful of epic battles with the power to alter the political landscape still feature.
The fate of all of Parliament's six minor parties, except the Greens, is likely to be decided in electorate tussles, while the individual futures
of another five sitting MPs may depend on whether they win marginal seats.
Under MMP a party's overall number of seats is decided by their party vote. Parties must either cross a 5 per cent voting threshold or win an electorate seat to enter Parliament.
Five of the six minor parties are polling below 5 per cent in an average recent polls, meaning they are likely to need an electorate seat to re-enter Parliament.
Crucial and marginal seats:
TAURANGA
In 1999, New Zealand First leader Winston Peters' last gasp victory by 63 votes in this seat saved his party from oblivion; in 2005 his loss to National MP Bob Clarkson by 730 votes removed a vital lifeline.
Then, his party won 5.7 per cent of the party vote, returning seven MPs to Parliament.
This time around NZ First is under siege - seemingly entrenched at below 3 per cent in an average of recent polls. An electorate seat could be its final fingernail hold on Parliament.
Mr Peters is facing an uphill battle with the only published poll on the seat showing him trailing National's candidate Simon Bridges by 20 points.
Mr Bridges, 31, is one of National's fresh faces. The lawyer and crown prosecutor has the backing of a local party organisation that by all accounts has strengthened its grip on the seat over the past three years.
Add to that several weeks already spent on the hustings while his rival has been tied up dealing with several inquiries into his funding and the odds look stacked against Mr Peters.
But with his party's survival possibly riding on a win, Mr Peters will pull out all the stops.
In 2005 he went to the lengths of parading a former female staffer of Mr Clarkson who claimed sexual harassment.
If Labour becomes desperate either an endorsement of Mr Peters to its voters or the pulling of its candidate in a bid to give Mr Peters a boost is not outside the realms of possibility.
OHARIU, WIGRAM
United Future leader Peter Dunne and Progressives leader Jim Anderton need to win their respective Ohariu and Wigram seats, but they both hold such strangleholds on them they are hardly worth discussing. Over the years they have made them their own political fiefdoms and should romp home by large majorities.
EPSOM
Epsom is a closer call, but ACT leader Rodney Hide should beat the National candidate he defeated in 2005, list MP Richard Worth.
Mr Hide's 2005 win was a big upset, but National's reselection of Mr Worth - who is seen as an only average performer - is seen as a sign it is not seriously contesting the seat, which is a lifeline for its potential coalition partner.
THE MAORI SEATS
The Maori Party will also probably rely on an electorate seat to return to Parliament, but in their case it is not a question of whether they will win one, but whether they will win all seven.
Last time around they took four, which now look safe and their sights are set on the other three.
The toughest battleground staked out so far is Ikaroa Rawhiti, which pits Maori Affairs Minister Parekura Horomia against veteran broadcaster and Maori Party candidate Derek Fox.
The campaign is a rematch of their epic 1999 tussle, which saw Mr Horomia step out of gunsmoke 695 votes ahead of Mr Fox, who was then standing as an independent.
This time around, a June Marae-Digipoll gave Fox a 1.5 per cent lead - well inside the margin of error.
In his favour Fox is a high-profile candidate and the Maori Party has considerable momentum, but as the hulking Mr Horomia shrugs off his ministerial duties to campaign full time he will be able to point to several key Labour policy gains.
They include a deal protecting local iwi Ngati Porou's customary rights under Labour's foreshore and seabed legislation, several Treaty deals and key economic gains for Maori such as low unemployment, big rises in the minimum wage and the Working for Families package.
Expect a tight tussle.
Hauraki-Waikato - a slightly altered and renamed version of Tainui - could be another tight battle. Labour's Nanaia Mahuta defeated Maori Party candidate Angeline Greensill by 1860 votes last time around.
An early Marae-Digipoll put her in front of Ms Greensill, but only just.
She has tradition and Kingitanga blood on her side and after her 2005 efforts was rewarded with ministerial roles - all things that should hold her in good stead.
But the Maori Party's continued rise and some voters' fatigue with Labour after its nine years in government mean all bets are off.
Te Tai Tonga, which takes in Wellington and the South Island, is also expected to be a tight fight.
Labour's Mahara Okeroa took it last time round by a comfortable margin, but this time around he is seen as vulnerable to new Maori Party candidate, Treaty lawyer Rahui Katene.
If Mr Okeroa loses, his 40th position on Labour's list could also see him exit from Parliament.
TAUPO
Former minister Mark Burton held this seat for Labour in 2005 by 1285 votes, but boundary changes which see Taupo incorporate the National stronghold of Cambridge from Piako and lose Taumarunui to the Rangitikei electorate leave him extremely vulnerable.
Cambridge returned a 1600 majority to National in 2005, while Taumarunui returned a 57-vote majority for Mr Burton.
Mr Burton is ranked 39th on Labour's list, but five candidates below him have a better than even chance of winning seats meaning a drop of 1 per cent in Labour's rolling poll average of 35.7 per cent support would see him jettisoned from Parliament.
Those five candidates - ranked 45-49 on the list - are Clare Curran in Dunedin South, Grant Robertson in Wellington Central, Chris Hipkins in Rimutaka Iain Lees-Galloway in Palmerston North and Brendon Burns in Christchurch Central.
HAMILTON-WEST
Labour MP Martin Gallagher beat National candidate Tim MacIndoe by 825 votes last time. This is a rematch, but Mr MacIndoe is likely to be ahead if any of the swing to National in opinion polls is reflected in electorate votes.
At 41 on Labour's list Mr Gallagher would be gone on current polling, assuming five seats are won by those below him on the list.
PAPAKURA
Labour list MP Dave Hereora is contesting the seat against National's Clevedon MP Judith Collins. The seat is a new one and contains parts of Ms Collins existing electorate, but is believed to be relatively neutral territory for Labour and National.
Ms Collins is an energetic campaigner, while Mr Hereora is reserved. At 42 on Labour's list Mr Hereora's return to Parliament could depend on winning the seat.
WEST COAST-TASMAN
In 2005, Labour Minister Damien O'Connor held what has traditionally been a safe Labour seat in its party homeland by just 2154. He should hold it again, but expect a tight tussle. If Mr O'Connor loses, at 37 on Labour's list, he could be vulnerable if Labour's vote drops.
OTAKI
This is the most marginal seat in the country with Labour's Darren Hughes holding it by just 382 votes from National list MP Nathan Guy. It will be a tight battle, but both MPs will return to Parliament courtesy of high list positions even if they lose.
ROTORUA
Labour Minister Steve Chadwick, then a backbencher, won this seat by 662 votes in 2005.
She faces a challenge from National's new candidate Todd McClay, son of former National minister Roger McClay. However having recently returned from overseas Mr McClay is an unknown face and may struggle to make headway. At 30 on Labour's list, Ms Chadwick's return to Parliament - even if she loses - appears secure.
- NZPA