In an unusual move, the youth wings of Parliament's eight political parties have come together to show their backing for a bill allowing same-sex marriage.
They said their combined show of support in a short presentation outside Parliament on Monday reflected the overwhelming support for marriage equality among younger New Zealanders.
The bill in the name of the Labour MP Louisa Wall amends the Marriage Act so that two people - regardless of their sex, sexual orientation or gender identity - can marry.
Young National Party vice-president Shaun Wallis says Young Nats have been urging MPs to support this issue from the start.
Mr Wallis says there is a generational shift in favour of same-sex marriage.
Young Labour spokesperson Sam Thompson says marriage equality is the number one policy priority for the party's youth wing. "It fosters a community of equality, fairness and freedom," he said.
New Zealand First's Curwen Rolinson says its youth wing is united in supporting a referendum on the issue.
All the representatives say there is a generational shift in favour of same-sex marriage.
The second reading of the Marriage (Definition of Marriage) Amendment Bill is due on Wednesday. At its first reading 80 MPs voted for the bill and 40 against, in a conscience vote.
Ms Wall says the country's young political leaders have sent a clear message to MPs to vote in favour of the bill.
She says their unusual move sends a powerful message to MPs ahead of the bill's second reading.
"I think it will be a factor in their decisions because we as members of Parliament ... have to create legislation that's relevant to the lives of New Zealanders. And what we do know is that there is strong support for young New Zealanders."