Labour will oppose a bill setting up the two referendums deciding the fate of the flag because of a sticking point over the order of the questions.
The Flag Referendums Bill is expected to get its first reading in Parliament soon and has enough support to pass its first stage without Labour, although the Maori Party and the Greens have only committed to support it through to select committee so far.
The bill sets out the process and questions for the two referendums - expected to cost $26 million. The first will be later this year and ask voters to choose between four options for a new flag. The second will pit the most popular new flag design against the current flag and ask voters to pick one.
Labour's Trevor Mallard said voters should be asked whether they wanted to change the flag in the first referendum. "There should be a yes/no vote at the beginning of the process so that if the majority of New Zealanders don't want change we don't spend a fortune on an unnecessary second referendum."
He said all the parties represented on the cross-party flag committee other than National held the same view. NZ First is the only party which refused to take part in that.