KEY POINTS:
Outgoing Trade and Defence Minister Phil Goff is set to become the new leader of the Labour Party to follow Helen Clark, but the deputy leadership could be a contest.
In the running are expected to be veteran minister Annette King and possibly former Health Minister David Cunliffe.
Ms King would be the favourite at present.
A vote, however, could be avoided through a negotiated transition.
Outgoing Prime Minister Helen Clark announced that she would resign as Labour leader after the election defeat.
"It's over and out for me," she told shocked party members.
Deputy leader and Finance Minister Michael Cullen also announced yesterday he would step down.
The caucus will meet in Wellington tomorrow, but with no clear deputy emerging it is unlikely that the leadership issue will be resolved then.
Mr Cunliffe has been tipped as a future leader of the party but on Saturday night said: "I will not put my hand up for leadership. I will not accept the nomination if someone else offers it to me."
He said Labour was a collectivist party. "Wisdom will be shared, and I wouldn't be surprised if people come to a pretty shared collective view." Mr Cunliffe did not, however, rule out standing for the deputy's post if it became vacant.
Shane Jones has also been tipped as a possible leadership prospect but has fallen from favour, not least because of his handling of the "showerhead" fiasco at the start of the election campaign and his decision in August to grant residency to controversial wealthy businessman Yang Liu against official advice.
Trevor Mallard was tipped by Helen Clark in 2000 as a potential successor, but his star has fallen in recent years.
Mr Goff appeared to be the only leadership contender yesterday, with less certainty around the deputy's post.
Former president and outgoing Housing Minister Maryan Street last night ruled herself out of contention for deputy.
The caucus will be weighing whether to go with a younger generation of MPs and future leadership prospect in Mr Cunliffe, with the inherent tensions that could create - or go with an older, safer pair of hands in Annette King.
Geography could be a factor against Mr Cunliffe. He and Mr Goff are both from western Auckland seats - Roskill and New Lynn - though neither lives in his electorate.
Mr Cunliffe would be the front-runner to take over the finance portfolio under a Goff-King leadership combination.
Dr Cullen has not yet indicated that he will be relinquishing the finance role as speedily as the deputy's post, but he is expected to hand it over to a younger face.
Maryan Street would be a contender for health or education, and Clayton Cosgrove and Darren Hughes could expect promotion.