NSW Labor MPs are bracing for a "bombarding" final week of campaigning by leadership contenders Chris Minns and Jodi McKay, as they make last ditch appeals for their colleagues' support.
Both candidates are expected to focus their lobbying efforts on a group of MPs who have not declared publicly or privately who they intend to vote for in Saturday's leadership ballot.
As the campaign enters its final week, supporters on both sides said they believed the caucus vote was "close".
"The only people you can trust are the ones who tell you they aren't going to vote for you," one MP said.
According to another MP, the closeness of the caucus vote had heightened the stakes for the undeclared MPs and said "self-interest would obviously come into play" over the coming week.
"If you pick the wrong side, you have potentially cruelled your chances for promotion in the short term," the MP said. "There will be a pretty ruthless bombarding of the undeclared and undecided members."
Another MP said they expected there to be "intense discussions throughout the week" about "who is the best person to lead us to government".
Acting leader Penny Sharpe and returning officer for the ballot Daniel Mookhey, by virtue of their positions, have not revealed who they plan to support.
Other undeclared MPs include upper house MLC John Graham, Newcastle MP Tim Crakanthorp, and Macquarie Fields MP Anoulack Chanthivong.
The renewed focus on the caucus vote comes after the campaign for the rank-and-file vote ended last week, with almost 10,000 of the ballots returned by the deadline on Friday. More ballots are expected to trickle in, with party officials hopeful of a return rate of around 60 per cent of the approximately 17,500 ballots posted to members. The rank-and-file ballot will be counted alongside the 50 caucus votes on Saturday, with the results of each group given a 50 per cent weighting in determining the outcome.
If the caucus vote proves tight, the outcome may turn on which candidate was more successful at getting out the vote.
A senior Labor source said the unpredictability of the member-vote meant the result was "wide open".
Mr Minns and Ms McKay were provided with membership contact lists by the party's head office and, with the help of the volunteers, directly canvassed members by phone.
However, both camps say they ran distinctly different ground campaigns. According to his supporters, Mr Minns ran a more "systematic" and "organised" campaign that targeted big Sydney branches, particularly those surrounding his south Sydney seat of Kogarah.
Summer Hill MP Jo Haylen and upper house MLC Rose Jackson, both key backers of Minns in the party's left wing, promoted his campaign to the populous inner Sydney branches.
While a large proportion of the Labor membership is concentrated in Sydney, Ms McKay's supporters claimed her "grassroots, organic campaign" reached more people and a higher voter turnout would "dilute" Mr Minns' pockets of support.
"The more votes that come in, the better it will be for Jodi because she is more widely known than Chris," one MP said.