David Shearer's future as Labour leader is now in serious question after he was effectively shafted by delegates at his party's weekend conference.
Shearer was already under huge pressure to deliver a blockbuster speech when he addresses the conference today. That speech is now almost the least of his worries. Yesterday's conference proceedings were an unmitigated disaster for the already-struggling leader.
Delegates were so blinded and so intoxicated by the prospect of securing a say in the election of future leaders that they did not think through the consequences and have ended up undermining the current one - quite possibly fatally.
So keen were delegates to get the new rules to apply as soon as possible, they have handed David Cunliffe a golden opportunity to mount a challenge to Shearer. Cunliffe is not likely to waste that chance.
Cunliffe now needs the backing of only 13 other MPs in the 34-strong Labour caucus to trigger the first party-wide leadership election when Shearer's continued tenure comes up for the standard mid-term re-endorsement in February.
If Cunliffe gets the numbers to force a vote, Shearer's position as leader will become untenable and he will have little choice but to resign.
John Armstrong has absolutely nailed it. Rather than the 2012 conference uniting Labour's caucus, it is now more bitterly divided than ever. The will of Labour's rank and file will prevail, but the collateral damage will be severe and long-lasting.