When departing leader Bill English counselled the National caucus not to make public declarations about which candidate they would be supporting as leader, it encouraged a greater level of secrecy than is usual with leadership contests.
It has inevitably led to a high degree of speculation as to which of the 56 MPs will be supporting which of the four candidates.
The Herald's Press Gallery team has put together our best guess as to which way MPs may be leaning.
For example, Mark Mitchell is the only candidate to welcome the prospect of Steven Joyce remaining as finance spokesman, so it could be logical to assume Joyce would support him.
And Simon Bridges attracted a number of public declarations of support when he stood against Paula Bennett for the deputy's role in 2016 and we have assumed they are sticking with him.
It was done without asking any of the candidates to vet the lists, and with a week to go until the vote, it will be updated.
It does not claim to be a definitive list because many MPs are undecided.
This first list shows suggests that Simon Bridges and Amy Adams are well in front of Judith Collins and Mark Mitchell but that Mitchell has more support in caucus than Collins.
It also suggests that if the two leading contenders, Bridges and Adams, are close, the contest will go to a vote rather than having a negotiated outcome. In that case, where the supporters of Collins and Mitchell go could be crucial.
SIMON BRIDGES 22
Simon Bridges, Kanwaljit Singh Bakshi, David Bennett, Gerry Brownlee, Sarah Dowie, Paul Goldsmith, Joanne Hayes, Harete Hipango, Brett Hudson, Nuk Korako, Todd McClay, Ian McKelvie, Simon O'Connor, Chris Penk, Shane Reti, Jami-Lee Ross, Stuart Smith, Scott Simpson, Tim van de Molen,Hamish Walker, Jian Yang, Jonathan Young.
AMY ADAMS 22
Amy Adams, Maggie Barry, Paula Bennett, Chris Bishop, David Carter, Jonathan Coleman, Jacqui Dean, Matt Doocey, Andrew Falloon, Chris Finlayson, Nathan Guy, Nikki Kaye, Barbara Kuriger, Melissa Lee, Tim Macindoe, Todd Muller, Erica Stanford, Anne Tolley, Louise Upston, Nicky Wagner, Michael Woodhouse, Lawrence Yule.
JUDITH COLLINS 3
Judith Collins, Simeon Brown, Parmjeet Parmar.
MARK MITCHELL 9
Mark Mitchell, Andrew Bayly, Bill English, Steven Joyce, Matt King, Denise Lee, Alfred Ngaro, Alastair Scott, Nick Smith.