If the contest between Simon Bridges and Amy Adams looks close, it will go to a vote on February 27.
But if someone emerges as a clear winner, and Simon Bridges' team is the more confident, a managed result is more likely to minimise the appearance of disunity.
One of the best examples of a managed result was in 2006 when Bill English, with not a chance in the world of winning, said he would contest John Key for the job of leader vacated by the hapless Don Brash.
There was no foundation of friendship on which to base a deal - in fact the opposite because there were suspicions in the English camp that Key had double-crossed English when he lost the leadership to Brash in 2003.
But English had leverage because he had two assets.
First he had a group of dedicated supporters who felt disgruntled under Brash with the potential to go on feeling disgruntled under Key if English wasn't treated better.
He also had something Key wanted: the best credentials as a former Finance Minister to replace Key as finance spokesman. Key did not want Brash or Brash acolyte Lockwood Smith in finance.
Over the weekend before the vote was due to take place, English had enough leverage to get himself the deputy leadership as well – with Gerry Brownlee standing aside to avoid the vote.
English had the discipline to stick to the deal and for 10 years showed not an iota of ambition for Key's job. The facetious criticism of each other
Bridges exudes ambition and having him as deputy to Adams would be a recipe for instability.
So where are the parallels with 2018? Any deal would involve two roles but possibly three, leader, deputy and finance spokesman.
A Simon Bridges leadership with Amy Adams as deputy and with finance is possible.
Adams exudes discipline and could be Bridge's deputy. But Bridges exudes ambition and having him as deputy to Adams would be a recipe for instability, real or imagined.
Deputy leader Paula Bennett and finance spokesman Steven Joyce complicate matters.
Bennett says she wants to stay as deputy so that gets her to the negotiating table.
She could be part of an alternative deal with Bridges as leader, Bennett as deputy, Adams in finance and high places for Judith Collins and Nikki Kaye.
The points of difference from Labour would be a male leader, two Maori in the leader and deputy leader - one of them from Auckland - and a front bench dominated by women.
Gerry Brownlee would go back to his role as shadow leader of the House, which he does brilliantly.
That would leave Amy Adams in the pole position to take over from Bridges in 2020 if he could not lead the party into Government.
The prospect of Bennett keeping the deputy's job is higher with Bridges than it is with Adams. It may be 2018 but apparently it would be not acceptable to have women in both leadership roles, leader and deputy.
Joyce is problematic. He is mulling over whether to stand, ultimately because he is not especially wanted by either of the two main contenders to continue as the party's chief strategist or finance spokesman.
With political sainthood having been bestowed on Bill English since the announcement of his departure, Joyce and Bennett are the last ones of the old guard taking the rap for every ill of the campaign and the failure of post-election coalition talks.
Labour has had the most recent experience of a managed result, with the elevation of Phil Goff after the defeat of the Fifth Labour Government in 2008.
But one of the most audacious examples of a managed result was last year when Kelvin Davis became Jacinda Ardern's deputy on August 1.
Grant Robertson would have won hands down, had he put himself forward in an open contest.
But under crisis circumstances close to an election, there was need for a swift and clean result and the Maori caucus exercised their leverage to secure the deputy's position during negotiations the day before Andrew Little formally resigned.
It also ticked more boxes in terms of balance, which is becoming increasingly important in the two big parties.
There hasn't been a moment's questioning of it since then because who would care after Labour won power.
In all of National's leadership changes in the past 34 years, there have been only two caucus votes: 1984 when Jim McLay beat Jim Bolger and sitting leader Rob Muldoon; and in 2003 when Don Brash beat Bill English in an open contest.
In other cases, there has either been a letter presented to a sitting leader (to McLay by Bolger, to Bolger by Shipley, to Shipley by English) or a negotiated result, for Key's ascension in 2006 and for English's ascension in 2016.
Judith Collins was one of only five of the current caucus who were present for the last vote, in 2003 (English, Brownlee, Nick Smith and David Carter were the others).
She will be wanting the process this time to go the distance because her support is primarily outside Parliament - grass roots members and voters and the odd talkback host – and is based on them lobbying sitting MPs. The more time, the more chance of momentum.
If it goes to a vote and she drops off as the third candidate, where her supporters go in the second round could be crucial to the result.
But if the outcome is managed, Collins is not without leverage herself.
Any candidate with a small but dedicated group of supporters can make an impact.
