After every change of government, dismal polls become a staple for the political misery that is Opposition. But there are dismal polls – – essentially temporary bouts of opprobrium and uncertainty unleashed by the electorate on the recently vanquished — and then there are polls so dismal that one must start to question whether they represent some underlying shift afoot in the size and structure of a party’s base vote.

We’ve seen the latter in action before, particularly at the State level, with leaders like Peter Beattie applying some WD40 to rusted on Coalition voters and forever changing the political landscape as a consequence.

But what is happening to the Coalition and Brendan Nelson is unprecedented.

The problem here of course is trying to estimate what the Coalition’s base vote actually is, or rather was. With a number of state Labor governments of late carving out pretty extraordinary majorities, it appears that the proportion of the electorate that that will only ever vote for the Coalition over Labor at any level of government has been shrinking for a while. If we look at state and federal elections over the last decade and for each state take the lowest primary and two party preferred vote that the Coalition has received in an election, we’ll get a fairly good idea of just how big, in practice, that group of the electorate is that will always vote for the Coalition over Labor under any circumstance.

So for NSW, the lowest primary vote achieved by the Coalition was 33.7% in 1999. However, there was a large One Nation effect running through that election which distorts the picture, so if we look at the 2003 State election we find the Coalition received a 35% primary vote with a TPP of 43.8%. So we’ll use this as our NSW Coalition base vote figure. If we do the same for all the states and use federal results for Tasmania (because of their Hare-Clark system) while paying particular attention to avoiding any One Nation distortionary effects around 1998, we end up with the following lowest primary and two party preferred results received by the Coalition recently in major elections.

Primary 35 38.2 35.5 34.4 36.1 37
TPP 43.8 42.2 44.5 47.3 43.2 42.7

We can then use state electoral population weights to get a national average of 36% for the Coalition primary vote base and 43.8% for the Coalition two-party preferred vote base, which represents the lowest possible level of Coalition support based on the actual putting of pen to ballot paper by the electorate. Our base vote estimate isn’t meant to compare State and Federal politics; it is simply an estimate of the proportion of the electorate that has never voted Labor over the Coalition in major elections — the truly rusted on Coalition vote.

If we run these two base vote lines against a seven year history of the federal Coalition primary and two party preferred vote estimates (using monthly Newspoll averages to knock out some of the size of the poll to poll noise), something extraordinary happens:

Now remember folks, this base vote is calculated on the sheer thumpings that the Coalition has received in the States of late, so it is probably a little undercooked in real life and would in reality probably be up to a couple of points higher than the red lines given here. Effectively, this is the Coalitions’ best base vote scenario.

Brendan Nelson is leading a party that is receiving a national vote share lower than all of the state Opposition annihilations of late put together. It makes the polling bleakness of early 2001, and that of March/April 2007 look like a golden age of popularity by comparison.

If that’s not bad enough, if we look at the way those State annihilations of the Opposition played out in practice, a sort of electoral hysteresis was operating. State ALP governments eroded the State Coalition vote to the point where the Coalition base started contracting, leading to an almost natural, lower long-term level of Coalition electoral support as a result — a level of support from which the state Oppositions have found it almost impossible to recover from, consigning themselves to a generation of political failure.

If you lose your base, you lose your political viability. The Nelson Opposition is losing their base vote in an unprecedented fashion.