John Key: the popular New Zealand PM has led his party to three election victories. (Phil Walter/Getty.)

In choosing the destination for his inaugural overseas trip as prime minister, Malcolm Turnbull might be doing a Narendra Modi. When India's leader was elected, speculation blossomed as to whether he might travel first to China or the US. He chose the safe option and went to neighbouring Bhutan. For his part, Mr Turnbull is taking the short flight across the ditch to New Zealand — he arrives here this afternoon.

But Australia's new leader is probably much more interested in emulating his trans-Tasman host. John Key is well into his third term as prime minister and has no obvious challengers. His finance minister and able deputy Bill English has just delivered a budget surplus, making the deficit mountain Scott Morrison has to climb seem even steeper. The NZ National Party is well ahead in the opinion polls.

There is no shortage of admiration for the NZ PM and Treasurer in Australia. The contrast between the affable stability of Key and English and the poisonous chaos of the Rudd-Gillard-Rudd-Abbott era in Australian federal politics could hardly be more marked. In Malcolm Turnbull, could Australia have found its own version of the New Zealand leader who, in all likelihood, will go on to triumph in four successive general elections?

On the surface, at least, this appears possible. Turnbull seems a less polarising and more sensible figure than any of his predecessors. He is probably closer to Key in his political instincts than any recent Australian leader. Both men have an eye for the political middle ground and are at the socially liberal end of their parties. Like Key, Turnbull will probably be fiscally careful without wanting to rip up what remains of the welfare state. Both have professional backgrounds so they are in tune with the needs of the private sector and have had lives beyond politics. And when it comes to foreign affairs, Turnbull will bring a more measured touch than Abbott

Yet there are at least four reasons to question whether Turnbull will be an Australian version of New Zealand's popular leader. Firstly Turnbull has come to power by virtue of a party room spill, rather than a general election. This makes him more of a pawn in ongoing factional battles. In convincing his colleagues that he is conservative enough, Turnbull has the Australian version of the Tea Party to contend with. Key's leadership is, and fairly much always has been, rock solid.

Second, Key came to power confronting two acts of nature for which his government could not be blamed. The first was the global financial crisis. The second was the Christchurch earthquake. Guiding New Zealand through these serious challenges while maintaining a modicum of economic growth, and then extending the rate of growth, has been the Key Government's signature tune. The economic and budgetary problems Turnbull inherits are also partly due to events beyond Australia's control, including China's weakening demand. But Turnbull was also a senior minister in the Abbott Government, whose unique ability to paralyse parliamentary business made things worse for the economy. And he has more form. The sixty-year-old Turnbull has been in parliament for over a decade during which time he lost the Party leadership to Abbott. Key became prime minister at 47 when he had been in the House for just six years.

Third, Key's predominance has coincided with a consistently woeful opposition from a Labour Party still under the shadow of a departed leader. Helen Clark, now gunning for the top UN job, continues to cast a spell over the New Zealand left. By supporting the recently agreed Trans-Pacific Partnership, she has pulled the rug from under the feet of Opposition Leader Andrew Little. This is not to say that, from across the Treasury benches, Turnbull faces an ALP opposition of historic renown. But in the Abbott era, Bill Shorten achieved poll results that New Zealand Labour Party leaders since Clark have only dreamed of.

The fourth point is that John Key's style is very hard to emulate. He sometimes talks extemporaneously to a point that must worry some of his more cautious advisers. But this disarming approach works. He speaks to New Zealanders through the media in a way few leaders have done. And he's actually very likeable.Turnbull has many strengths as a politician, but it will be difficult for him to emulate John Key's style in the big west island, and not just because the Australian media is more brutal and thorough.

Turnbull may also leave himself open to attack by taking the issues of the day too seriously. Nobody can accuse John Key of being a swat. He often gives the impression of making it up as he goes merrily along. But on some of Australia's tricky policy issues, from climate change and water use to taxation, state-federal relations, migration, health and education, Turnbull appears keen to display his fondness for detail and complexity. If so, it will be difficult for him to replicate one of Key's great strategies: when the dirt starts to fly, smile and say that you, and your office, simply didn't know.