Labour's leadership is telling the annual party conference that it's ready to present a united front with the Green Party going into next year's general election.
The two parties signed a memorandum of understanding six months ago, committing to co-operate in the lead-up to the vote.
In his address to delegates on Saturday, Labour president Nigel Haworth said under New Zealand's mixed member proportional voting system, the party must embrace its relationship with the Green Party.
"Let me be clear, a party confident in its values and purpose and operating in an MMP environment must embrace fully the potential offered by such arrangements," he said.
"The MoU reflects the maturity and depth of our politics and is a very good thing."
Labour leader Andrew Little earlier invited Green co-leaders James Shaw and Metiria Turei to join senior party members on stage for the conference opening, while Mr Shaw was also invited to speak.
"When we signed a memorandum of understanding between the Green Party and the Labour Party six months ago we sent a message of hope to New Zealand that that change [of Government] is coming," Mr Shaw said.