When rumours of a leadership coup in Labour broke on Tuesday night, I bumped into a Green MP as I was racing back to the office.
The first question we asked ourselves is "who is it?"
We speculated about David Cunliffe and deputy Grant Robertson.
Grant's not ready, I said. Grant is definitely ready, the MP said.
I also thought about Andrew Little. He had a boost from the last Herald-DigiPoll survey which had him almost matching Grant Robertson in terms of a suitable replacement for Shearer were he to suddenly depart politics.
It was the same poll that began this round of jitters because Shearer's popularity fell six points and the party's by almost the same amount to 30.9 per cent.
Anyway, by the end of Tuesday night, it was clear there was no coup under way by Robertson or anyone else.
But Shearer's chances of being replaced before the next election had increased.
At the start of the week, I would have put his chances of surviving at 80/20. Now they would be closer to 50/50.
That's for two reasons: first the party has not united behind him since the leadership contest with Cunliffe in 2011, and the "man-ban" issue has reinforced the disrespect the party has of him; and secondly because public talk about a coup can help to make it happen.
The Labour MPs who took to Twitter were angered because they knew that even having to deny it makes the possibility that much more plausible.
There may not have been a letter of no-confidence circulating on Tuesday, but it is drafted in some people's minds, if not their bottom draws.
A letter of no-confidence would need 50 per cent of the signatures plus one to trigger a wider vote, so 18 signatures from a caucus of 34, or 17 were a vote to be held between the time Lianne Dalziel resigns for a tilt at the Christchurch mayoralty and is replaced.
The caucus would comprise 40 per cent of the final vote, the party 40 per cent and the affiliates 20 per cent.
(The threshold for a party-wide leadership contest is lower in the caucus confidence vote required after an election - 40 per cent plus one).
The coverage of the whole "man-ban" issue has exposed the party's fundamental flaws: its factions, the tensions between the caucus and the party, and the perception that the party is overly concerned with issues of identity.
Amid the leadership issues, there has been a serious debate internally in Labour this week about the wisdom of Maryan Street promoting her euthanasia private members' bill.
Labour is terrified it will be drawn out of the ballot.
The debate would extend into election year and give the Conservatives another platform to boost its support as a potential partner for a third-term National Government.
Despite the talk of a no-confidence letter, in the event that things got very bad for Labour, it is unlikely that Shearer would need a letter.
The more likely scenario is that party seniors and faction brokers Phil Goff and Annette King, would tell him: it's time, David.
He would resign and a new leadership contest would begin.
How bad would it have to get? There are two reputable polls set to be published in the next few weeks: TV One's and TV3's.
May's TV One and TV3's polls both had Labour on 33 per cent, and Fairfax's had it on 31.9 per cent. Including DigiPoll, three of the four polls have Labour heading south.
It is hard to imagine that the "man-ban" issue (allowing some electorates to have women-only selection contests) and subsequent coup talk has done anything but damage.
Shearer looked decisive for half a news cycle. The lasting image is not of a strong leader but one being kicked by one side of his party for not acting sooner and kicked by the other side of the party for acting at all.
The poor man is beginning to get the public's sympathy, not its support.
The question is whether that downward spin has begun from which there is no recovery.
If Labour were to drop into the 20s in all three polls, that would be understandable given recent events.
If it were to stay there for three months, it would be fatal to Shearer - Goff and King would come knocking. Then the battle would get interesting.
Would the party go with the candidate that could get them closest to Government but risk further disunity in the party, Cunliffe?
Or would it risk going with the lower profile deputy, someone less likely to get them into the Government, someone with less public appeal (nothing to do with him being gay) but more likely to unify the party?
This is the Robertson dilemma. He might be ready but is the public?
Cunliffe is the candidate that National believes is the greatest threat to John Key. Several ministers have said so privately. By that reasoning he is the candidate that Labour should choose.
He has behaved well for eight months now, with no undermining of the leader. He is a polished performer.
According to DigiPoll he would be the preferred replacement by 31.8 per cent of all voters (against 16.6 for Robertson and 13.5 for Little) and 37.7 per cent of Labour voters (19.1 for Robertson and 14 for Little).
His detractors believe that were he to be elected leader, the wider electorate would tire of him quickly, as many of his colleagues have.
Robertson is a less polarising figure, not tested as a minister, respected in Parliament and in the party but less known by the public.
His backers installed Shearer, the complete novice.
Talk of no-confidence in Shearer has not been identified as coming from either the Cunliffe or Robertson camps.
It has destabilised Shearer's weakening leadership. But replacing Shearer with either Cunliffe or Robertson would be as risky as the move was to put in Shearer.
In the event of failure, the party could be forced to contemplate a second leadership contest closer to the 2014 election with a wild card such as Shane Jones, Little or even back to Goff as leader were Robertson or Cunliffe unable to steer the party away from a disastrous result akin to Bill English's in 2002 of just over 20 per cent. None of these scenarios is out of the question.
As the party's Labor cousins across the Ditch have demonstrated, the prospect of electoral defeat trumps everything as the driver of desperate political action.