Labour Party deputy leader Grant Robertson still appears to have the greatest support in caucus for the party's leadership vote, but David Cunliffe's supporters say the gap is closing.
Mr Cunliffe has the backing of some of the affiliated unions but they only make up a small proportion of the final vote.
The vote to select the new leader is weighted 40% to caucus, 40% to party members and 20% to affiliated unions.
One of the MPs supporting Mr Robertson believes they have the votes of two thirds of caucus.
An MP in Mr Cunliffe's camp estimates the number of MPs supporting Mr Robertson is closer to half the caucus, or 17 MPs.
Mr Cunliffe's supporters say he has about a dozen MPs backing him. Radio New Zealand has counted ten.
Both the Robertson and Cunliffe camps believe the third candicated, Shane Jones, has about four votes in caucus.
Roadshow nears end
The three candidates met in Blackball, the spiritual birthplace of the Labour Party, on the West Coast on Monday night.
The meeting was the second to last gathering in a roadshow taking the hopefuls around the country to make their case to those eligible to vote for the leadership.
In a town of 300, about 70 people from the region filled the Blackball Working Men's Club.
Mr Robertson told the the audience Blackball had left an important legacy for the Labour Party.
"The struggle for workers' rights, the struggle for recognition of the contribution of workers to our economy, the struggle for a fair day's pay for a fair day's work in New Zealand began in this town," he said.
Mr Jones said the country needs a government committed to regions like the West Coast.
He said he supports the mining industry and sees no reason why the country's natural resources should not be used to create jobs.
Mr Cunliffe also voiced support for the mining industry. He said if he were elected Labour leader he would try to get the victims of the Pike River mining disaster a fair compensation package.
The new Labour leader will be announced on Sunday.