Given how close the two men are, it was fascinating to see how much of Christopher Luxon's State of the Nation speech was a break with the fiscal and political strategy of the John Key years.
Key's first big speech in 2007, delivered just a few streets over from the state house where he grew up, was an audacious raid into Labour's political territory.
Key argued for more social spending and a greater focus on poverty and hardship than anyone was expecting from a National Party leader at the time.
The speech placed him firmly in the centre ground of New Zealand politics, a position he never let go of.
With Key, the pitch went, voters could get a strong economic manager but someone with a powerful social conscience as well.
Yes, he would balance the books, pass business-friendly policies and offer targeted tax relief, but he would do so while raising the minimum wage, raising benefits, investing in health and education and keeping debt low.
It was, for those middle-ground voters who sometimes vote for Labour and sometimes vote for National, the best of both worlds.
By contrast, Luxon's speech, and the tax cut promise at the centre of it, seems to be directed much more at a true-blue National Party audience than the lower and middle income voters that Key courted so effectively.
It was a policy programme that could comfortably have been announced by any of Judith Collins, Todd Muller or Simon Bridges.
Firstly, there's the sheer size of the tax cuts. At roughly $3 billion year, Luxon has spent more on one tax policy than Key did in new operating allowances for any of his eight budgets. That means with one policy, Luxon is putting more money into tax cuts than any of Key's budgets had for new spending on health, education, welfare, public services, infrastructure and tax cuts combined.
It makes it very hard to see how National would have enough money available to keep up with rising costs for things like schools, hospitals and infrastructure.
Secondly, there's the question of who these cuts are targeted at. Luxon's decision to nix the top tax rate and undo the Government's tax changes for rental properties means that the lion's share of his cuts aren't going to people struggling with the cost of living.
In fact, nearly half of all the money he is spending will go to people who either own multiple homes or make more than $180,000 a year. Meanwhile, someone earning $40,000 a year will only get around $2 a week – ironically just enough for a packet of chewing gum or two.
Luxon could easily have kept tax settings the same for the very well off in order to give low and middle income-earners a bigger slice of the pie, but made a deliberate political call not to.
Thirdly, by going for cuts of this magnitude, Luxon is all but guaranteeing he won't be able to bring down debt levels all that much faster than the Government is planning, forgoing the promises to balance the budget that were a key feature of many of Key's campaigns.
There's no doubt Luxon's speech has worked well for him so far – it tightened the screws on a Government already hurting politically over the cost of living. Luxon is clearly betting that inflation is so out of control that he can win back middle-income voters on this issue alone, without having to make the wider policy pitches Key used.
But in the longer term, Luxon's big tax cuts may be setting him up for trouble. By not focusing enough on lower- and middle-income voters he's giving the Government time and space to shore up that ground. And by going out with such a massive promise so early without detailed costings, he's leaving himself very little ammunition for election year and opening himself up to tough questions about whether his plan actually adds up.
After all, if there's one line from the Key years that haunts all opposition leaders, it's "Show me the money."
● Hayden Munro was the campaign manager for Labour's successful 2020 election win. He now works in corporate PR for Wellington-based firm Capital Communications and Government Relations.