Phil Goff and Annette King have emerged from caucus to confirm that they will step down as leader and deputy leader of the Labour Party.
Their resignations will take effect from December 13 although both will remain as MPs.
Candidates in the running to replace Goff include David Cunliffe, David Parker, David Shearer, Grant Robertson and Nanaia Mahuta, but Goff has refused to reveal who he supports.
Earlier, Newstalk ZB reported party numbers were fairly evenly split between Cunliffe and Parker.
iPredict has David Parker slightly ahead of David Cunliffe to succeed Goff at 53 percent to 40 percent.
Prior to leading the Labour Party, Goff enjoyed stints as minister for almost every conceivable portfolio, starting with Minister in Charge of Government Life Insurance Corporation in 1984.