The Mana Movement and the Maori Party will today unveil a plan to work together at this year's general election.

They'll formally sign an agreement in Whangarei where they will outline how they will co-operate in the Maori seats and who will stand aside where, to ensure chances of winning seats are maximised.

The move could potentially pull the balance of power away from New Zealand First leader Winston Peters.

AUT History Professor Paul Moon told Mike Hosking the Maori Party is likely to work with the National Party on supply issues and the Mana Party could be on board too.

He said such an agreement would make them "quite a strong voting-block".

Mr Moon said Labour had been aware of the deal for some time, which is one of the reasons it tried to promote Willie Jackson as a high-profile Maori candidate.

"It looks like Andrew Little tried to get that and didn't succeed, it just backfired on him because he obviously had ... MPs that weren't happy about it.

"It's looking worse and worse for Labour."