Mondayising Anzac Day and Waitangi Day is all but a reality after Prime Minister John Key confirmed this morning that he expected a Labour MP's bill on the matter to pass into law and ruled out using the Government veto on it.

Labour MP David Clark's members' bill to allow a day off on a Monday if the two public holidays fall on the weekend is expected to get its second reading in Parliament on Wednesday.

National does not support the bill, claiming it will put too much load on businesses and would detract from the significance of the dates.

However, Mr Clark has secured the support of the Maori Party ad United Future as well as Opposition Parties - giving it just enough support to pass without Government support.


Mr Key said National's decision to oppose the bill was "a line ball call right from the start" and its caucus had been fairly divided on the issue.

"So our view is that the status quo should continue, but I imagine it will pass. We won't veto it."

He said it was highly unusual for an Opposition member's bill to pass without the support of the main governing party, but it would be "disingenuous" for National to start supporting it at this stage.

"I don't think people would have believed it. We'd had a view, it was a line ball call from the start and there was a mixture of views in the caucus but in the end we took the view it was better to stay with the status quo and I think people would see through it if we changed now."

He said it was a marginal call whether the Government could have invoked its veto on the bill - it is allowed to block legislation that has an adverse fiscal impact, as it intended to do with Sue Moroney's bill to increase paid parental leave.

Mr Key said most of the cost of the Mondayising bill was on the private sector rather than the Government.

"We reserve the veto for Government expenditure and there is some Government expenditure, but it's not huge. I think at the margin we might have been able to [use the veto] but we would have been stretching it a bit. The world is not going to cave in as a result of it, it will please some people and some people will have a holiday on a day they might not have otherwise got.

"It's six of one and half a dozen of the other."