Changes to electoral boundaries will leave some MPs nervous about their futures, with at least five seats likely to be tight battlegrounds.
The contests for Rotorua, Taupo, both Hamilton seats, and West Coast-Tasman are expected to be close.
Changes to electoral boundaries were confirmed by the Representation Commission yesterday. There is one new electorate - Botany - which is centred on the fast-growing Flat Bush area of Manukau City.
The new boundaries will be in place for at least the next two elections. National is now claiming to be within cooee of taking Taupo and Rotorua from Labour, while Labour hopes to get Hamilton East and the South Island Rangitata seat from National.
Cabinet ministers Mark Burton (Taupo) and Damien O'Connor (West Coast-Tasman) are among those whose electorate seats will be closely fought. And unless he's saved by a good list placement, the boundary changes could spell the end for National's David Bennett in Hamilton East.
Until the next election, the more interesting battles will be within the parties themselves as potential candidates fight it out to win selection.
Brian Connell, who remains on the outer in the National Party caucus could be at the end of his time in Parliament.
His Rakaia electorate has been dismantled and merged into a Selwyn electorate which includes National list MP David Carter's home.
The boundary changes open several electorates for MPs to squabble over, and some sitting MPs have already indicated they will retire, opening the way for others to win safe seats. Wellington Central's Marian Hobbs is retiring, leaving her seat open. Paul Swain's Rimutaka will also be up for grabs.
The Hamilton seats have traditionally been volatile - but changes to Hamilton East and Hamilton West make them a safer bet for Labour by trimming the National-supporting rural outskirts of the city from the electorates.
Mr Bennett said the change effectively wiped about 10,000 votes from the electorate - many of them rural National supporters.
"It is pretty good for [Labour.] It makes it tough. The Hamilton seats have always been marginal, but this is a totally urban seat now so it will be a battleground."
He does not yet know who he will be facing - Labour's Dianne Yates, from whom Mr Bennett won the seat by 5300 votes, is set to retire from politics.
Labour President Mike Williams said Martin Gallagher's hold on Hamilton West was strengthened by the change.
National says Mr O'Connor's West Coast-Tasman seat is now "the most marginal in the country" after taking in some small settlements from the Nelson electorate. Mr O'Connor holds the seat with a 2154 majority - easily assailable - but Mr Williams said the MP was very popular and had little to fear.
Taupo And Rotorua
Labour minister Mark Burton's slim hold (1285 majority) on Taupo is more shaky with the inclusion into the Taupo electorate of Cambridge providing rich pickings for National.
Changes to Rotorua to include more rural land heading out to the East Coast could also see Labour's Steve Chadwick topple. She won the seat by 662 votes, the second-smallest majority in the country.
Based on voting patterns of former election results, National is estimating changes to Rotorua and Taupo will give them an extra 1000 electorate votes for each seat.
National is expected to win the new electorate of Botany - but both National and Labour say it makes their surrounding seats safer - Papakura and Hunua will be safer for National, but Manurewa and Manukau East will be safer for Labour.
Other electorates are also significantly changed to take account of population growth in Auckland - Northland will now stretch down to include Wellsford as other electorates - including Rodney, Helensville and East Coast Bays are squashed up because of higher population in those areas.
Banks Peninsula becomes Port Hills and becomes predominantly urban - shuffling the farming land of the peninsula into the Selwyn electorate. The change boosts Labour's Ruth Dyson likelihood of holding onto the seat - and leaves her 2005 National Party rival David Carter to pursue the adjoining, rural Selwyn electorate.
Mr Carter said he would seek selection for Selwyn, which includes his farm, effectively blocking Mr Connell.
The MP says he has not made a final decision on his future, "but if I do stand, [Selwyn] is where I would stand."
Mr Williams said most of the South Island was a "stay put" situation, but was hopeful of Labour's chances in Rangitata - which pulls into one electorate the blue-collar towns of Timaru and Ashburton.
National's Jo Goodhew has a 7000-vote majority in Aoraki, the seat which Rangitata absorbs.
Mr Williams hoped Labour could regain it, blaming Jim Sutton's defeat on his commitments as trade minister, as well on the the public backlash about Prime Minister's motorcade speeding through Timaru.
"Jim went from a significant majority to being 7000 down to National, so I wouldn't be surprised if that had an impact."By Claire Trevett @CTrevettNZH Email Claire