John Key's strategy for winning three elections was simple: do nothing. Continue all of Labour's policies (which he had denounced as "socialism" while in opposition) while not meaningfully changing them (or maybe eroding them slowly). It was unpopular on the right, but very successful at winning elections, because it turns out that kiwis like socialism and don't much care who delivers it.
But that has consequences. Last week the press gallery was all about the consequences for Labour, who were forced left to differentiate themselves (which was apparently bad because they lost Nick Leggatt). But there's consequences for National too, in that Key's sustained political strategy has effectively created a political consensus.
Look at the platforms of the three leadership candidates. How many of them are advocating full Ruthanasia as a way of appealing to the backbench? None. How many are explicitly opposed to tax cuts, and instead arguing for increases in public spending on social services? Two. And the one who isn't doing that - Bill English - is pretty lukewarm on tax cuts, because unlike John Key he can count.
(Update: Actually, English thinks there are higher priorities than cutting taxes. So that's three for three).
Basicly the party of "slash the state" has instead become the party of "manage the state, if not moderately increase it". And as someone who likes left-wing policies, I again find it difficult to think that this is a bad thing.
But its not just a consensus against austerity. Look at the way policy has flowed over the last eight years. Under a National government, you'd expect policy to be flowing from ACT: ACT comes up with a crazy idea, convinces National's donors and a few backbench MPs, and National does it. Instead, policy has been flowing in the opposite direction: the Greens push for something (a capital gains tax, mass home building), they convince Labour, who convince the public, and National is forced into doing it in order to hug the centre. And while they do it in weaker form (a two-year bright line test, fewer homes), it establishes a consensus which can later be strengthened. Next time there's a Labour government, that two-year bright line test will become a permanent capital gains tax on investment properties (and maybe on shares too), and there will be more homes built. And National won't be able to oppose it except on managerial grounds. And if they leave the mild socialist centre and return to their traditional policies, they'll find themselves struggling, because taking care of people is popular.