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.
His only option is to convene an emergency caucus meeting and secure a motion bringing forward the vote on his re-endorsement, which, if held now, he would win.
He instead risks becoming a victim of his own passiveness.