David Cunliiffe is expected to be demoted at an emergency Labour caucus meeting this afternoon.
The meeting is ostensibly to confirm David Shearer's leadership. But with the vote a foregone conclusion (Mr Cunliffe has already said he will back the leader, for now), the gathering has become all about retribution.
But a political scientist is warning that if Mr Shearer does banish Mr Cunliffe from the frontbench the move could backfire.
"A disaffected politician can lob verbal grenades from the backbenches so any punishment should be mild," Auckland University associate professor Raymond Miller says.
In Mr Miller's view, Mr Cunliffe damaged his changes by mis-timing his challenge. "Political leadership is all about timing," the Auckland academic says, and the annual conference was the wrong place and the wrong time.
And Parliament will soon go on its summer hiatus, leaving the challenger with few opportunities to undermine Mr Shearer before the scheduled leadership vote in the New Year.
"In February there's every possibility Shearer will survive," Mr Miller told TV One's Breakfast programme.
With victory all but in the bag, it would be counterproductive to push Mr Cunliffe to the margins, where he would likely cause trouble.
Commentator Brian Edwards has also warned about yielding to the temptation to demote Mr Cunliffe, whom he sees as Labour's most effective debater.
Dr Edwards noted that Helen Clark – who had her own leadership troubles in opposition – kept her enemies close. Or as LBJ put it, "Better to have them inside the tent p*ssing out, than outside the tent p*ssing in."
Punish Hipkins instead - Trotter
Meanwhile, keeping things stirred, high-profile left-wing commentator and Truth columnist Chris Trotter says Labour senior whip Chris Hipkins is the one who should be dealt to at today's caucus meeting.
Yesterday, Mr Hipkins crticised Mr Cunliffe as "dishonest", "disingenuous" for hinting at a February challenge without openly playing his hand. "Weasel words about supporting the leader for now simply don't cut it," Mr Hipkins said.
"I have never seen an opposition unleash a torrent of abuse to equal to Chris Hipkins yesterday," Mr Trotter said on Firstline.
"Mr Hipkins really deserves to be reprimanded by his party for an absolutely unprecedented attack on a fellow MP."
But Mr Trotter concedes a majority of Labour MPs are not on Mr Cunliffe's side. "They clearly had him."
Rule change favours challenger
Mr Cunliffe has not formally challenged Mr Shearer, but refused to endorse him as Labour's conference began over the weekend, and was among supporters of a rule change that will make it easier to challenge the leader.
A challenger now needs the support of just 40% of caucus to trigger a leadership vote.
In a second change, if a leadership vote is triggered, it will now include not just caucus. A new "electoral college" system will see Labour MPs' votes count for 40%, Labour Party members' votes 40% and affiliates such as unions 20%.
The new setup means Cunliffe must gain the backing of 14 of Labour's 34 MPs to force a leadership vote. He currently has 10 in his camp by most counts.