Such is his popularity that the Prime Minister could probably insist that black is white and then immediately turn around and argue the complete opposite without anyone seeming to care very much.

Apart from the Labour Party, that is. John Key's penchant for getting away with saying things that contradict his previous remarks has long been a source of frustration for Labour.

Key is more than Teflon Man. Whatever the DuPont chemical company may have come up with by way of improving its legendary product, Key seems to be the one chosen to test it.

Nothing sticks. Take mining in national parks. Phil Goff came to Parliament yesterday with a bucket-full of contradictory prime ministerial prognostications which he intended to pour over Key.

Having ascertained that the Prime Minister still stood by all his comments on the subject, the Labour leader wondered how Key could square last October's claim that modern mining required only a "surgical incision in the land" with the Prime Minister's refusal on Monday to rule out opencast mining in sensitive, protected areas.

Key's response was to give his increasingly familiar "aw shucks" shrug like a schoolboy caught with his hand in the biscuit tin, all the time grinning from ear to ear.

But just as his inquisitor thinks he or she has got the better of the Prime Minister comes the rehearsed riposte.

Key's comeback to Goff was to remind him that Labour had approved the Pike River mine on the West Coast, with the then Conservation Minister, Chris Carter, insisting it did not represent an intrusion into an area of high conservation values even though it was sited on conservation land adjacent to the Paparoa National Park.

Goff's deputy, Annette King, also pursued the inconsistency line, asking Key if he could recall telling New Zealanders that around 4000 jobs would be created from the national cycleway when, in reality, only 56 had been generated, most of them lasting between only three and 14 weeks.

Key's response was pure Dirty Harry. If Labour wanted to campaign on "ripping up the cycle trail", then they were welcome to make his day.

Less clear after yesterday's exchanges was the degree to which Key might be backing off mining on conservation land, given his reluctance to release the discussion document which canvasses the options.

However, the hints of backdowns before the discussion document has seen the light of day must set a record in terms of political caution.

No matter that little more than a month ago the opening up of the conservation estate to mining was cited as one of the vital ingredients in the Government's plan for a "step change" in the pace of economic growth.

However, such inconsistency may work in Key's favour and perversely be one reason behind his staggering preferred prime minister ratings.

Labour is playing the conventional political game which assumes inconsistencies, flip-flops and u-turns are cumulatively corrosive on a Prime Minister's standing with the public.

Key, however, is unconventional. He does not believe in consistency for consistency's sake. If something's not working, then change it. If something is unpopular, there has to be a good reason for persisting with it. It may be poll-driven.

It may be highly pragmatic. Witness the swift back-track on cutting pensioner use of the SuperGold Card. Key doesn't muck around. Whatever, the public seems to like it. And Labour is left chasing his shadow.