Labour MPs will be given less than two days to pledge their loyalty to newly-elected leader David Cunliffe or face reassignment of their duties.
Dunedin North MP David Clark and Dunedin South MP Clare Curran both told the Otago Daily Times yesterday they were 100% behind Mr Cunliffe after his ''clear and strong mandate''.
Both MPs had publicly supported Grant Robertson in the leadership contest but Dr Clark said Mr Cunliffe had won in a rigorous, vigorous and transparent process.
Opponents of Mr Cunliffe will need to express unreserved support or face life on the backbenches or retirement at next year's general election.
When caucus meets tomorrow morning, pledges will be expected on the table.
Key supporters of the new leader, Iain Lees-Galloway, Rajen Prassed, Sue Moroney, Carol Beaumont and Moana Mackey, will expect some reward for their support, against the early wishes of their colleagues.
One of his first major decisions will be the appointment of a deputy, likely to be a female.
With few female MPs in the South Island, the chances are high an Auckland woman MP will be deputy leader, which may alienate some of the southern supporters. No South Island women MPs supported Mr Cunliffe.
Mr Cunliffe won the leadership on the first ballot with 51.15% of the vote. Mr Robertson received 32.97% and third contender, Shane Jones, received 15.88%.
More than 60% of party members voted for Mr Cunliffe in the first round and nearly 71% of union affiliates backed him.
In the caucus vote, Mr Cunliffe got the support of 11 MPs, Mr Robertson 16 and Mr Jones seven, on the first ballot.
Mr Cunliffe received 47% of the second preference vote (32.35% in first ballot) from his fellow MPs and Mr Robertson had nearly 53% of the vote (47.06%), meaning the second preference votes from Mr Jones, who received 13.15% on the first ballot, were evenly spread.
One of the first indicators of whether the caucus will unite behind Mr Cunliffe, who has been a polarising figure in the past, will be the appointment of chief whip.
Current chief whip Chris Hipkins has been an outspoken critic of Mr Cunliffe, while aspirant Mr Lees-Galloway campaigned for Mr Cunliffe.
Mr Hipkins has been in devastating form in the House, taking on Education Minister Hekia Parata, while Mr Lees-Galloway is considered solid and steady, rather than a shooting star.
After his election, Mr Cunliffe promised the focus of his leadership and the entire party would be on winning the 2014 election.
''We must beat [Prime Minister] John Key and we will only do that by mobilising the entire party, the affiliates, the membership and caucus.
"If we can combine the best of all of us, the winners will be the people of New Zealand.''
Any Labour government he led would champion full employment and a fair go for all New Zealanders, he said.
Raising taxes would be an election policy for Labour under his leadership.
He fought back tears as he thanked those who had supported him.
''This is not a split caucus . . . this is a united caucus.''
Mr Robertson said he was disappointed to be beaten but he supported the process and the outcome.
He said it was too early to talk about future leadership aspirations and he was absolutely committed to serving Mr Cunliffe.
Asked whether he would rule out another run at the leadership, he said: ''I'm 41.''
He added that it could be a possibility after Mr Cunliffe served ''three or four terms as prime minister''.
Dr Clark said his future role in Parliament would be decided by Mr Cunliffe but felt his support of Mr Robertson would not hinder his chances.
Ms Curran said she had been loyal to the two previous Labour leaders, Phil Goff and David Shearer, and she would be as loyal to Mr Cunliffe.
Ms Curran caused some controversy last week with an ill-timed comment on Twitter accusing opponents of Mr Robertson playing the ''gay card''.
Whether that comes back to bite her will be known early this week.
Mr Jones, a list MP, received the news at the Manurewa RSA. After the result, he said it had been an invigorating race, and the new Labour leader would have his unstinting support.
He would not put his name in the ring for deputy leadership and he was keen to see a female MP take on the role.