The Green Party says low-earning contractors at Parliament, not core public sector workers, should be first in line for a living wage.
In a speech at the Council of Trade Unions conference this morning, Greens' co-leader Metiria Turei said her party would have a different priority to Labour in distributing a minimum wage of $18.40 an hour - known as a "living wage".
Labour leader David Cunliffe said at the conference yesterday that if his party was elected, he would make sure that all core public sector employees were paid this amount.
Ms Turei, whose party was a long-time supporter of the living wage campaign, said some workers outside of the core public sector had a greater need for a pay rise.
"We are so pleased that the Labour Party has made such a strong commitment to a living wage and to a living wage for the core public service.
"But we are also committed to making sure that those people who led the campaign for a living wage, that those who put themselves at the forefront of a political war over decent wages, that those who have taken the greatest risk in this campaign, and those who need the living wage the most are the first off the block.
"They are our first priority."
The party was still calculating the cost of raising wages for the lowest-paid contractors, but Ms Turei said she believed it was relatively inexpensive.
At present, Parliament's cleaners earned $14.10 an hour.
Later this month, Opposition MPs will spend a night working alongside the cleaners in Parliament to draw attention to what they feet is unequal employment conditions and wages.