Poll of polls

NEW ZEALAND HERALD: The long-term trend in opinion polls has been up for National and down for Labour. From an average lead over National of 10 percentage points early in the last election year, 2005, Labour goes into the final months of this election year 25 percentage points behind - 30 per cent to National's 55 per cent.

Labour's dip coincides with a slump in mood and consumer confidence to levels not seen for a decade or more.

But even if Labour was on trend, the straight line on the graph, it would still be 18 percentage points behind (34 per cent to 52 per cent). And the trend is important: no matter how often this chart has been updated since the 2005 election, the two major parties' trendlines have always shown Labour 2 points ahead of National at that election, which was the result.

Labour's challenge is to reverse the trend. For a year up to April this year, both Labour and National appeared to have steadied, which might have been the precursor to a reversal. So far, that has not been the case. Since April, support for Labour has plunged.

* The poll of polls is a rolling average of the four most recent polls at each point. Since five polls are included, one is necessarily missing from each point and sometimes a poll will feature twice. The five are Herald-Digipoll, TV1 Colmar Brunton, TV3 TNS, Fairfax Neilson and Roy Morgan. UMR was included in earlier data but UMR has withheld data since April.