Can the late change to Jacinda Ardern as leader work for Labour?
Fifty-odd days out from the election, Labour has turfed out its leader, hoping for a bounce in support from Andrew Little's replacement, Jacinda Ardern.
There's precedent for this.
In 1990, the Labour Party found itself in a similar situation - terminal polling numbers with an election looming.
Labour replaced Prime Minister Geoffrey Palmer with Mike Moore, just 35 days before the election. Polls had Labour on 28 per cent and Palmer on 16 per cent as preferred Prime Minister.
By his own admission during an interview for RNZ's Ninth Floor series, Moore was brought in to "save the furniture". In other words, Labour couldn't win the election, but needed to reverse a trend in the polls that had seen their support halve since 1987.
Labour won 35 per cent of the vote - an improvement of seven points on the polls prior to the change. They still lost 28 seats in Parliament, but it could have been much worse.
ALL CHANGE IN AUSTRALIA
It had been decades since a major party changed leaders so close to a NZ election but it's become something of a tradition in Australia.
In 2010, Julia Gillard rolled Kevin Rudd and took the leadership of the Australian Labor Party just 58 days before an election. Labor was polling at about 35 per cent prior to the change.
Data from Australian polling company Newspoll shows there appeared to be an initial bump in support for Labor, but it fell away as the election got closer.
In the end, Labor won 38 per cent of the popular vote and lost 11 seats, but was able to stay in Government with the help of minor parties.
Three years later - almost to the day - the roles were reversed and Rudd rolled Gillard with Labor polling around 30 per cent 73 days out from an election.
The impact of this change was similar. Labor got an initial bump in the polls, but it didn't last and the party lost the election, winning 33 per cent of the popular vote.
Then there is the famous case of Bob Hawke, who took leadership of the Labor just 30 days before an election in 1983.
He took over from Bill Hayden on the same day that Prime Minister Malcolm Fraser called an election, seven months earlier than scheduled.
The short lead-in time can't have hampered Hawke, as Labor won almost 50 per cent of the popular vote and a majority of seats in the Parliament. Hawke would remain as Australian Prime Minister until 1991.
It doesn't quite qualify as last-minute, but New Zealand Labour did make a change about one year out from the last election, swapping David Shearer for David Cunliffe.
Labour had been polling in the 31-33 per cent range under Shearer. There was a small increase in support for Labour in the first poll after the change, but it didn't last.
By June 2014 Labour support was below 30 per cent in the polls and kept sliding until election day when the party won 25 per cent of the vote. Labour still hasn't recovered to the levels seen under Shearer, who has since quit politics.
WHAT CAN BE LEARNT?
Of course none of these cases can tell us what will happen to Labour under Jacinda Ardern. There are a multitude of different factors unique to each of these scenarios.
However, they do seem to challenge the view that a late change creates instability, which turns voters off.
In three scenarios above where a new leader came in very late in the piece, the party managed to, at the very least, slightly improve support on election day compared to polling before the change.
And it does seems possible that new leaders get an initial bump in the polls - perhaps the publicity that comes with a change is worth a couple of points on its own - but sustaining it can be difficult.