The first poll to test voter reaction to last week's publication of the "Dirty Politics" book shows the government maintaining its lead over the Labour Party, rising 2 percentage points to 48 percent, while Labour has dropped 2.5 percent to 27.5 percent.
However, the Roy Morgan New Zealand poll cannot be said to give a full picture of reaction to the book, by political journalist and activist Nicky Hager, because its sample polled 809 people between Aug 4 and 17, whereas the book was only published late on Aug 13. (See graph below)
The poll does show a rebound in sentiment about whether the country is on the "right" or "wrong" track, a long-standing political bellwether. Positive sentiment fell sharply to 60 percent in the poll taken over the second half of July, but rose to 63.5 percent in the latest poll.
Political party support again suggests that New Zealand First will be in a "king-maker" position after the election, but only to install a National Party administration. NZ First is shown polling at 6.5 percent, which would entitle the party led by Winston Peters to eight parliamentary seats.
At 48 percent support, National would be entitled to 58 seats, three short of a majority in the 120 seat Parliament. While it might hope to cobble together a majority, that would depend on all three of its current support partners - the Act, United Future and Maori parties - each winning an electorate seat, as none is polling high enough to return to Parliament on the basis of the party vote alone.
Under New Zealand's two-vote MMP voting system, parties enter Parliament in proportion to their share of the so-called "party" vote, but only if they win 5 percent or more of that vote. The only way to enter Parliament if the party vote is below 5 percent is if the party wins one of the smaller number of geographical electorate seats that are also up for grabs.
On that basis, National might need to look to NZ First to secure its majority for a third term in office.
The combined 39 percent vote for Labour and its likely coalition partner, the Green party, whose support slipped 0.5 percent in the latest Roy Morgan poll to 11 percent, would leave the centre-left 13 seats short of a majority. Even if the Internet-Mana party, polling steady at 2.5 percent support, were to enter Parliament with three seats, NZ First's additional eight would leave a four way tie-up with Labour and the Greens two seats short of a majority.
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