The narrowing of the gap between the major parties this week - putting them almost neck and neck in the Herald's analysis of the polls overall - has probably ensured the election result next Saturday will be close.
Until the Reid Research poll for TV3 was published on Tuesday night, some National voters were probably looking at third parties, pondering how to influence the composition of a Labour-led coalition.
The poll putting National 10 points ahead was out of line with most others recently but it put National firmly back in contention.
If it has discouraged strategic voting, it will have done our politics a favour. Undesirable things can happen when people do not vote for the party they really prefer. Voting for a minor party, unless it is your first choice, can have perverse results, particularly if the party is New Zealand First. Trying to predict what Winston Peters might do is a fool's mission, Peters himself has no idea what he will do until he knows the results and sees which way the wind is blowing.
If Labour finishes with more votes than National, he will probably go with Labour. But if National wins narrowly he might still go with Labour, deciding his voters want change. That assumes, of course that he retains the Northland seat and his party makes the 5 per cent threshold. Neither looks assured at this point. NZ First's share of the party vote declined this week and Labour's resurgence means Peters cannot count on the Labour voters who helped him win the Northland byelection two years ago.
It is one thing to vote for a third party candidate in a byelection that cannot change the Government, quite another to give your electorate vote to a candidate who might, or might not, put your preferred party into power. Best to vote for the party you want unless another party has given a cast-iron indication of its intention, as the Greens and Act have done.
NZ First and the Maori Party are the unpredictable elements in the election, though it is likely the Maori Party would prefer to be in a Labour Government this time. Its nine years with National, while important for the party to establish its ability to work with both sides, has put it under stress. Its MPs represented electorates that continued to give the bulk of their party votes to Labour.
If Labour needs the Maori Party for a majority after the votes are counted next Saturday night, the stress will be felt by Labour's Maori MPs. The smaller party poses a threat to their hold on Maori seats.
If the Maori Party was to rule out another term with National whatever happens, it might greatly lift its party vote in Maori electorates, giving it enough seats to be in a strong bargaining position with Labour.
If the Greens clear the threshold, a threesome with Labour and the Maori Party could well take NZ First out of the equation. That would be a blessing for both sides. It is blemish on MMP that it allows the votes of millions to be over-ruled on the whim of one individual. But those who vote for Peters give him the latitude to do what he wants. They seem indifferent to what he decides, but there are fewer in his camp now than when the race began.
National and Labour are both in contention as the campaign enters the final week, and their voters will be concentrating on the contest that matters.