The Mana and Māori Parties will confirm the details of their co-operation agreement for this year's election on Monday.
The agreement was expected to involve deals over electorate seats, with the shared aim of winning all seven Māori seats.
That could include the Māori Party standing aside in Te Tai Tokerau to give the Mana leader Hone Harawira a better chance of beating Labour's Kelvin Davis.
However, Māori Party co-leader Marama Fox was reluctant to confirm any details ahead of the announcement.
"Well what we know from recent dealings with a certain Mr Jackson, nothing's done 'til it's signed on the dotted line so you'll find out on Monday."
Both parties have previously said they had learned from their mistakes at the last election, and wanted to take a much more constructive approach this time around.