Simon Bridges is believed to be ahead in the National Party leadership contest but is still short of the numbers required and at risk of being overtaken if the vote by National's MPs goes into a second round of voting.
The winner next Tuesday will need at least 29 votes out of National's 56 MPs to secure the role.
It is increasingly doubtful any of the five contenders - Bridges, Amy Adams, Steven Joyce, Mark Mitchell and Judith Collins - will get to the magic 29 before the vote, although a substantial number of MPs appear to be still undecided.
The candidate who gets least votes is eliminated and further ballots are held until somebody gets to 29.
That has meant the candidates have had to lobby strategically to try to secure pledges for the second-round votes of those MPs backing a rival.
Most MPs are still remaining quiet on how they will vote, but Bridges is widely acknowledged as being ahead, with Amy Adams behind him.
If it goes to further rounds of voting, Adams could overtake him on the "second preference" votes.
The other contestants are Mark Mitchell, Steven Joyce and Judith Collins.
There has been speculation some candidates will withdraw over the weekend, but all said they intended to see it through.
As well as lobbying for support, the candidates have been leaping through the hoops for the media - each has been put through a "speed dating" session on TV1's Seven Sharp as well as various radio and television appearances.
NZ First will also hold an election for its deputy leader next Tuesday. Ron Mark is the current deputy and expected to try to keep the job, although neither Tracey Martin or Fletcher Tabuteau will comment on whether they will go for it. Martin has held the job before.
Shane Jones said he did not intend to stand for it. "Because I'm going to be busy planting a billion trees. The pace is blistering. I have my priorities as a minister and someone else can stand up and do that mahi [work]."
Jones will launch his $1 billion a year Provincial Growth Fund in Gisborne tomorrow at an event with Prime Minister Jacinda Ardern and NZ First leader Winston Peters.