Why has National remained so incredibly popular for so long despite suffering continuing calamities, embarrassments and unwanted distractions, many of them self-inflicted?
Labour MPs this week went on the front foot, castigating National as a Government ''mired in scandals and more interested in deals with its mates'' than governing in the country's best interests. David Cunliffe, one of those MPs, went as far as describing John Key's second-term Administration as ''the rotting carcass on the body politic''.
Mr Cunliffe provided a long, but not exhaustive list of National's follies, including in no particular order: Warner Bros' muscle-flexing on The Hobbit; the Government's generosity in helping out radio and TV company MediaWorks; ''Banksie'' and Kim Dotcom; the failings of the Government Communications Security Bureau; the plunge into debt of state coal company Solid Energy; the dreadfully slow implementation of ultrafast broadband; backdowns on taxing employer-provided car parks and cellphones; and unemployment running at close to 7%. The public was counting the score, Mr Cunliffe added. In short, National was on its way out.
Well not quite. This week's Herald-DigiPoll put matters into perspective. Backing for Labour rose by more than four percentage points on the previous poll last August, the party registering more than 36% of the committed vote. It is Labour's best showing since late 2010.
But National edged up by a percentage point to 48.5%, thus maintaining a dominance in the poll dating back to John Key taking hold of National's reins in late 2006.
Mr Cunliffe's catalogue of calamities plus the inevitable wear and tear on a second-term government would have been expected to have a detrimental impact on National's fortunes.
Instead, Key-led National continues to enjoy a golden run in the poll which now stretches back 300-plus weeks.
The questions are obvious: how have Mr Key and National managed to defy political gravity and, perhaps more pertinently, for how much longer will they be able to do so?
It is possible to list at least 10 potential factors as being responsible, some of which are pretty clear-cut while others are simply untested, gut-feeling hypothesising.
The first factor is Mr Key's sky-high rating as most preferred prime minister. This is crucial in drawing many tens of thousands of uncommitted voters plus those with weak attachments to other parties to tick National. The ''brain fades'' and other lapses of 2012, a horror year for him and National, seem to have had little, if any, impact on Mr Key's own rating.
Labour has long targeted ''Brand Key'' in the belief that destroying him will destroy National. The strategy may have backfired, revealing Labour as petty and small-minded. Mr Key's failings may instead be viewed by the electorate as human, thereby increasing his rapport with voters.
Second, his moderate conservatism is in tune with the prevailing mood of the wider New Zealand electorate. Helen Clark understood that reality. But she still eventually fell victim to the conservative public's near hatred of Labour's supposed political correctness.
Third, Mr Key is unashamedly pragmatic - a word that used to be anathema to purists who stood four-square behind Sir Roger Douglas and Ruth Richardson in the 1980s and early 1990s. No longer. Ideology takes a back seat with Mr Key. There is no lecturing of the public as to the kind of policy prescription that ought to be swallowed. There is instead a ''no surprises'' approach, by and large. The Government does what it says it will do.
Even National's showcase policy of partial privatisation has a pragmatic element in the retention of a majority government shareholding.
The fourth factor is the neutralising of troublesome issues, rather than allowing them to linger and fester. In terms of resources, Steven Joyce has thrown the political equivalent of the kitchen sink at the faults in the Novopay payroll system for teachers. No doubt he would chuck the real thing in Talent2's direction if it might help.
Fifth comes the economy. Labour's recent private polling has confirmed a majority of voters view National as the better manager of the economy. They are likely to continue to do so in uncertain economic times. Why? Because Mr Key and Bill English have a proven track record in handling crises, like the Christchurch earthquakes, in a calm and unflustered fashion.
The Herald-DigiPoll had a majority of 49% to 43% agreeing the Government is moving in the right direction. National's Achilles heel can be summed up in three words: jobs, jobs and jobs. However, there are signs the economy is slowly picking up steam, as evidenced by this week's GDP figures for the last quarter of last year.
Sixth, National may have issued various vision documents which have ended up propping up shelves around the Beehive. However, the party is not all that good at articulating those visions. It is good, however, at maintaining momentum. It is essential a government be seen to be busy, otherwise it looks like it has stalled - and that is fatal.
Seventh, National is still largely defining what the arguments are about across most policy areas. In doing so, it's halfway to winning those arguments. Labour has yet to thrust a new dynamic - for example, a more hands-on style of economic management - on to the political agenda and lead debate on its terms.
Eighth, opposition parties are instead still devoting considerable time and effort to fighting battles they have lost - such as partial privatisations - or trying to land hits on National by raking over the coals of history, Solid Energy being the prime example.
Ninth, the public may be getting acclimatised to the at-times rather chaotic nature of minority government. Ms Clark's third term was marred by constant sideshows and distractions. Mr Key's second term has been similarly afflicted, but it has not been damaged. Voters may now be more willing to accept (or simply ignore) the ever-noisier political static if they can be assured National is focused on the bigger picture and getting things done.
Tenth and last, the political temperature is benign in terms of governing. Apart from asset sales there are few, if any, issues that are seriously divisive and on which National finds itself stranded on the wrong side of the argument for ideological reasons. Voters may be more tolerant, if not forgiving, of politicians' occasional lapses. Hekia Parata had to get an awful lot wrong before she lost the public's confidence.
Crucially, there's no mood for change, the real government-killer, or even much hint of such a mood developing. National may still lose next year's election, but only because of an absence of coalition partners. Its real enemy is MMP mathematics. It can't do much about that.
- John Armstrong is The New Zealand Herald's political correspondent.
