Anyone still pondering whether David Shearer is innately tough enough to cut it as a leader in the political rough-and-tumble now have their answer.
Having initially been out-manoeuvred by David Cunliffe at Labour's annual conference at the weekend, Shearer will today punish Cunliffe for his gross disloyalty by dumping him from Labour's front-bench, relieving him of his shadow economic development portfolio and consigning him to the backbenches.
Cunliffe will not be subject to motions suspending or expelling him from the caucus.
The last thing Shearer needs is to make a martyr out of Cunliffe among the wider party membership. But those sanctions always remain an option.
The Shearer camp is instead seeking to crush Cunliffe as a political force by destroying what is left of his credibility.
And with good reason. Shearer will win - and win easily - the leadership ballot which will be held at the special caucus meeting that the Labour leader has called for this afternoon.
But Shearer still has to win the ballot required under Labour's new constitutional rules and which will take place in February.
Moreover, the new rules approved at Labour's conference require that Shearer get the endorsement of more than 60 per cent of his colleagues in February's vote.
If Shearer gets less than that, a leadership election will be triggered under the new rules which give Labour's rank-and-file members a big say in who becomes the leader.
Cunliffe is seen as likely to pick up a large chunk of members' votes in any such election.
The Shearer camp is consequently trying to isolate Cunliffe and leave him so weakened he will not even bother to mount a fight in February.
Cunliffe has been his own worst enemy with his shifting stances on whether or not he would challenge Shearer.
Many MPs were angry with him yesterday for saying he would be backing Shearer in today's vote but then refusing to say whether that endorsement would extend to the February ballot.
While patience with Cunliffe ran out in some quarters of the caucus long ago, it is only now that some MPs are going public with their frustration.
By doing so, they are indicating that the Labour caucus would be seriously split if Cunliffe became leader.
It is a message to Cunliffe's supporters in the caucus not to push his cause too strongly because the caucus would become utterly dysfunctional under his leadership.
It is now for Cunliffe to decide whether he has any future in the Labour Party. Today's message to him will be blunt: this is your last chance to shape up. Otherwise ship out.