When he installed Annette King as his interim deputy, Andrew Little said he would revisit the decision around this point in his tenure. It's a promise he would be wise to break. The advantages of a generational swap between King and Jacinda Ardern, the widely touted alternative, are fewer than they initially appear, and the risks are greater.
(Full disclosure: Annette and I were quite close friends during the '90s but our acquaintance has cooled sufficiently that she failed to recognise me at a Titahi Bay fundraiser last year.)
Annette King is not a leadership rival to Andrew Little, nor is she likely to become one. The same cannot be said of Ardern. That's the first, and most crucial, box ticked. Unfulfilled ambition is the characteristic a leader least wants to see in a deputy.
King also enjoys near universal respect among her colleagues. Hardly an intimidating figure in the Helen Clark mould, "Aunty Annette" nevertheless inspires in Labour MPs a desire to get, and remain, in her good books. This is invaluable when you consider Little began as leader with very few caucus allies - only three MPs, plus Little himself, backed him in the leadership ballot over Grant Robertson and David Parker.
Combined with an absence of unrealised ambition, King's standing in caucus uniquely enables her to play hardball when called for, giving Little room to establish goodwill and build trust among colleagues.
It is hard to imagine an MP less temperamentally suited to inheriting "bad cop" duties than Jacinda Ardern. In fact, a change in deputy would demand a recalibration of responsibilities, forcing Little to take a greater role in managing (read: disciplining) caucus. He doesn't need that: it's not among his strengths, and it shouldn't be his focus.
Ardern certainly appears to be well liked by the public, and has the backing of many inside the Labour Party, as well as a sizeable bloc of MPs, in particular those aligned with Grant Robertson with whom she ran on a joint ticket as deputy in last year's leadership election. These are put forward as arguments in favour of promoting her, but they leave me cold.
For one thing, personal popularity is neither here nor there in a successful deputy. None of the most successful second-in-commanders of the recent era - Geoffrey Palmer, Don McKinnon or Michael Cullen - were beloved by the wider public. What they each offered were complementary skillsets, along with personal attributes, that made their leaders stronger.
Palmer's methodical, professorial demeanour dovetailed nicely with Lange's mercurial approach; McKinnon polished Bolger's rough edges; Cullen injected economic prowess and a taste for partisan combat. Such examples abound elsewhere: John Prescott, with his working class street cred, was the ideal foil for Tony Blair, and both Lionel Bowen and Brian Howe served Australian PMs Hawke and Keating well by keeping their heads down and the factions under control.
When a leader installs a rival in the second chair - Clark under Mike Moore, Julia Gillard under Kevin Rudd, Robertson under David Shearer - it is briefly heralded as a sign of strength until it becomes apparent, usually rather quickly, that the opposite is true. It never ends well. If King stands aside for Ardern, Little is presented with three problems he can avoid by persuading her not to do so. First, if Little simply swaps deputies, leaving his frontbench otherwise intact, he will create resentment among the bloc formerly aligned to Cunliffe - including two women of colour, Nanaia Mahuta and Carmel Sepuloni, who might justifiably consider themselves no less qualified for the role.
If he opts for a wider reshuffle to compensate for Ardern's promotion, the threat to caucus harmony is as obvious as it is avoidable.
Finally, Ardern for King severely depletes reserves of governing experience among the leadership group, a problem more pronounced in light of Robertson's weak performance to date in the critical finance role.
It may be that Annette King wants to retire - and who could blame her after 28 years in Parliament? This would bolster the case for Jacinda Ardern without making it a slam dunk. Breakfast telly affability - undeniably useful in a senior politician - is not what Andrew Little wants in a deputy. He needs a compelling or charismatic figure far less than someone who provides the space necessary for him to become effective and popular in his own right.
Phil Quin is a communications consultant who was an adviser to Labour in New Zealand (1989-96) and Australian Labor (1998-2001).