Winston Peters' choice between Labour and National is '50-50' - senior source

A senior source in New Zealand First has told Newshub it's "50-50" whether Winston Peters chooses to go with National or Labour-Greens.

The wooing of Mr Peters has begun in earnest, with both parties lining up their negotiating teams to try and convince the kingmaker.

Both will appeal to him for different reasons so it's hard to know who he'll go with and even within the party, it's a mystery.

While National's Bill English claimed victory in his election speech and has already made moves to talk with Mr Peters, the party isn't confident they'll end up as the winners.

A senior source in National told Newshub the party is worried Mr Peters may spurn them, so it's "taking nothing for granted".

Negotiations are expected to take some time, as special votes are counted, with Mr Peters repeatedly saying he won't rush into his decision.