National MP list Tau Henare spoke passionately in favour of a bill last night allowing people to swear to uphold the Treaty of Waitangi in official oaths but voted against it, along with the rest of his party.
He said failing to progress the bill told the rest of world New Zealand was just the same as all the other "colonial conquering nations".
He said he strongly supported the sentiments in favour of the bill expressed by sponsor Maori Party MP Te Ururoa Flavell.
"Unfortunately the whipping system says I cannot vote for his bill."
It is the closest a National MP has come to crossing the floor this term.
The bill would have allowed people to add words to the official oath: "I will uphold to uphold the treaty of Waitangi" or "Ka whakaungia e au te Tiriti o Waitangi".
The Oaths and Declarations (Upholding the Treaty of Waitangi) Amendment Bill was defeated, 69 votes to 48 so Mr Henare's vote either way would not have affected the outcome.
Mr Henare lamented the fact the bill was about to be defeated.
"We had an opportunity to say to the world that we were different than every other nation in the world."
Rejecting the bill said one thing: "That we are just the same as Canada, that we are just the same as Australia, that we are just the same as the United Kingdom and all the other colonial conquering nations around the world."
Mr Henare said it was with a heavy heart he would be voting against a bill which was non-violent, did not threaten anyone, didn't tell anyone what to do.
"I'll be voting against a bill which gave New Zealanders an opportunity to feel unique in the world."
He said he would like to cross the floor but "but if we have that sort of scenario going on all the time, you don't get stable Government".
The Maori Party, Labour, the Greens and Mana supported the bill.
It was opposed by National, New Zealand First, United Future and Act.
The Maori Party supports National on confidence and supply though its votes are not crucial.
Maori Party co-leader Pita Sharples said in statement this week that National's actions in opposing the bill contradicted is words in the confidence and supply agreement in which Prime Minister John Key acknowledged the status of tangata whenua and recognised the treaty as the found document of the country.
Mr Flavell said Naitonal's opposition was a disturbing move "which we might have expected from former leader Don brash for former Act MP Muriel Newman".
He said National risked looking as though it was shifting its position in response to pressure from a minority who promoted discontent over the treaty and Maori issues.