Labour's bill seeking to Mondayise the Anzac and Waitangi Day holidays has passed its first reading in Parliament.
The bill passed 61 votes to 60, with National and Act the only parties opposing it.
The bill would allow New Zealanders to have a day off on Monday when the holidays fall on a weekend.
United Future leader Peter Dunne, who voted in favour of the bill, said the financial implications of the change had been "grossly overstated".
"The impact of this is about once a decade so it's not going to break the Treasury, nor is it going to break the banks for businesses."
Tourism Industry Association chief executive Martin Snedden said it would boost domestic tourism and he called on all political parties to support the law change.
As well as stimulating domestic tourism, it was also a way of adding significance to the two occasions, he said.
"Some employers would be disadvantaged but given this situation will only happen for two out of every seven years, the cost is likely to be reasonably minimal."
The cost was outweighed by the overall effect on the economy, Snedden said.
Prime Minister John Key, who is also tourism minister, has said the change would cost $200 million each time a holiday fell on a Saturday or Sunday.
But Labour MP David Clark, who drafted the bill, called on Key to listen to representatives from his own industry.
"It's time the Minister for Tourism John Key stood beside the thousands of tourism operators who will benefit if every year Kiwis get the same number of public holidays."
The change would also support "hard-working New Zealanders," he said.
But Cabinet minister Judith Collins said Anzac Day was about mourning and commemoration and reducing it to a three day weekend was disrespectful.
"If people need to have a holiday to go and actually turn up at dawn parade, then there's something wrong."
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- With Newstalk ZB