The Labour Party is yet to decide whether it will back a law change which would allow people to swear an oath to the Treaty of Waitangi.
The private member's bill, sponsored by Maori MP Te Ururoa Flavell, was expected to be debated in Parliament tomorrow.
The legislation was set to fail, with the National Party and New Zealand First confirming they would oppose it at the first hurdle. National whip Michael Woodhouse said his party had seriously and respectfully considered the bill, but had "deemed it unnecessary".
New Zealand First leader Winston Peters previously said the bill was a "separatist" proposal which he could not support.
Labour had not yet decided whether it would support the legislation, and would discuss it in caucus this morning.
Mr Flavell's bill would allow any person taking a statutory oath to also say they would uphold the Treaty of Waitangi, including MPs who were being sworn into Parliament.
At present, the swearing-in oath reads: "I swear that I will be faithful and bear true allegiance to Her Majesty, Queen Elizabeth II, her heirs and successors, according to law, so help me God."
If the bill passed, MPs would be able to add: "I will uphold the Treaty of Waitangi."
Mana Party leader Hone Harawira was forced by Speaker Lockwood Smith to delay his swearing-in last year because he inserted a reference to the Treaty in his oath, instead of making a formal oath to the Queen.
In the past MPs from the Maori Party and some in the Greens have altered the swearing-in oath to include the Treaty of Waitangi before being stopped and told to deliver the correct wording stipulated by law.
The rules were changed in 2004 to allow MPs to give an oath in Maori or English.