Toby Manhire: Who wants to buy a hole?

Steven Joyce is becoming Big Bird - who talked so much about his imaginary friend that he became real. Photo / Supplied

Anyone want to buy a hole? This week the National Party smashed the emergency glass, tripped the alarm, and pointed, screaming, at a gaping void. There was an $11.7 billion hole in the Labour Party's fiscal numbers, said Steven Joyce, and they weren't fit to govern. The only question, he charged, was whether it was a balls-up or a swindle.

There is no hole, retorted Labour. There is a hole, hollered National. No hole! Hole! And on it went for several hours on Monday, before the economists gathered to peer into the abyss. One by one, these experts in the matter of holes shook their heads and pronounced that for all the road cones, flashing lights and hazard tape, there wasn't in fact a hole. The emperor had no spreadsheet. Wincingly, when asked yesterday to cite so much as a single individual who supported his central claim of an $11.7 billion lapse in Labour's accounting, National's finance spokesperson failed to name one. Except Bill English, that is.

Joyce insists that he does have some expert support, pointing to commentary suggesting Labour's plan left it with an emaciated operating allowance, in which most of the money was ear-marked for health and education. Opinions differ on that point, and there are clear grounds for criticism and questions. Opinions do not differ, however, on the central assertion levelled by Joyce. It isn't true. The only question is whether it was a balls-up or a swindle.

He could, of course, have summoned the press and expressed grave fears about Labour's numbers, about the approach they'd adopted, and about the leeway for future spending. But Joyce, the most effective campaign strategist of the last decade in New Zealand, would have known very well that such a statement would sink. To suck up the media oxygen, and therefore skew the imminent debate towards questions of financial competence, to stir up another "show me the money" moment, it needed to be big.

That the central claim has been shot down pretty much unanimously should be the end of it. But, slightly terrifyingly, maybe not. This is the world of illusory truth effect, in which veracity bends. As a paper in the Europe Journal of Psychology puts it, research shows that "repeating false claims will not only increase their believability but may also result in the false belief that they had been heard about previously and from more than one source". Fiscal hole is the Mr Snuffleupagus to Joyce's Big Bird - the imaginary friend that got talked about so much he became real.

It is obvious enough what has motivated National to sound the scare horn. A little over a month ago the Jacinda Ardern option was being talked about as a "save the furniture" tactic, in reference to the 1990 pre-election damage-limitation installation of Mike Moore. Suddenly their sofas are world famous. The television ad with National as a chirpy pack of fit joggers and the opposition a rabble tied together at the ankle was obsolete on arrival. Instead the blue-clothed runners are gasping to keep up, suffering from an acute but previously undiagnosed case of third-term-itis.

But as they slide behind Labour in the polls, the data point still providing succour to National is the right-track or wrong-track question. In most of the countries around the world that have in recent times witnessed dramatic voting shifts, similar numbers have indicated a clear appetite for change. Here, the September UMR survey found 56% saying the country is headed in the right direction and 35% thought it was on the wrong track.

That's slipped since the last poll before the 2014 election, which showed 59% right versus 31%, but only slightly. In the "drag race" with a "clear choice", to use English's mantra, and with the small parties squeezed out, National hopes it can yet prevail.

But the "relentlessly positive" approach that Labour's new leader has trumpeted makes it more difficult for National to lay claim to all of the right-trackers. It is a stark contrast to the bark-at-every-car opposition style of her predecessors. Ardern might have won an endorsement from UK Labour leader Jeremy Corbyn yesterday, but she is hardly a Corbynista. Ardern has even praised English's stewardship of the economy.

The right-track beacon also guides National's attempt to cast Labour as economic dunces. That steady hand on the tiller has been a crucial part of National's dream run - as English boasted this week, "I tracked every dollar for eight years as the finance minister".

He said that, however, as part of an argument around Steven Joyce's incantation of a fiscal hole - the hole that no independent number cruncher or bean counter has been willing to vouch for.

Last night's Colmar Brunton poll for TVNZ shows Labour extending its lead over National. That may be in part a punishment for Joyce's holier-than-thou effort to eviscerate Labour's economic integrity. It was a big risk to take, and stole oxygen from other available critiques of Labour, such as their vulnerability on its tax policy and Ardern's increasingly cloying default to values and appeal to "how people feel", with its whiff of truthiness. Crucially, though, coming on the back of a string of hasty, draconian, law'n'order policies, National's attack looks panicked, it looks cynical and it looks desperate. And it leaves the incumbent finance minister with a very serious credibility hole.