The Green Party's James Shaw is a pretty reasonable sort of fellow.
So it seemed an extreme thing for him to say during the election campaign this week that his party could walk away from a role in next Government and sit on the cross benches if it doesn't get what it wants.
It may have been stating the obvious, but it was hardly the message of petulance that he needed to send to voters, having only just recovered from a climb-down from $11.7 million worth of backing for a private school building.
It sent the wrong message –a throw-back to the dummy-spitting Greens whose principles are more important than the reality of compromise.
How is that message expected to attract a single new vote to a party struggling for survival - the latest leaked UMR poll has the Greens on 3.2 per cent (less than New Zealand First).
It wasn't something Shaw planned to say on Thursday. In fact he started the day at a campaign photo opportunity helping to lug bags of vegetables being delivered to the Wellington City Mission.
But after that, he was being probed by the Herald and Newshub about Green tax policy in the light of Labour's tax policy and whether the two sets of policy promises are compatible.
It raises questions about whether the word "promise" should even be used by MPs or media to describe policy under MMP. It may be an outdated term.
First past the post was voted out because politicians wouldn't keep their promises.
Ironically, this past week of the election campaign illustrates how it has been replaced with a system in which political promises are worth less than before.
MMP has other advantages. It means Parliament is more reflective of the community it represents and has parties such as the Greens – its antecedent, the Values Party, received more than 5 per cent of the vote in 1975 but no MP.
But MMP is a system in which promises are easily bartered away by parties in backroom negotiations after the election.
That is why it has become part of the stock in trade of journalists and commentators to work out in a campaign which are the truly non-negotiable promises.
That was apparent this week when Finance Minister Grant Robertson unveiled his tax policy – or as he prefers to call it, his revenue policy.
It is not about badgering politicians; it is about trying to get the politicians to properly signal if not articulate their degree of commitment to various policies rather than leaving it an educated guess.
Robertson is seasoned enough to engage in a semantic quickstep.
He was repeatedly pressed at his press conference but would not say that the proposed 39c tax rate on income over $180,000 was open to negotiation, that this new bracket would absolutely be implemented in any Government he was part of.
"Non-negotiable" was a term that was bandied around in the build-up to the first MMP election, before it became obvious it was not smart to spell out which policies were open to negotiation and which were not.
The term "bottom line" then replaced "non-negotiable" as being more MMP-friendly but even that term has become open to interpretation and Robertson would not say Labour's tax policy was a bottom line. He wouldn't rule anything in or out. He declined to even use such language.
What he said repeatedly was that "a Labour Government" would implement that tax policy.
He did not specifically define what he meant by "a Labour Government" but it was understood to mean a majority Labour Government that did not have to negotiate with anyone else.
It was so well understood that National leader Judith Collins was able to reasonably claim that Robertson had not ruled out negotiating additions to tax policy in any coalition negotiations with the Greens.
New Zealand First leader Winston Peters was incredulous that the single policy as announced was all there was to Labour's plans.
James Shaw was initially careful in his response to Labour's tax policy, calling it "tinkering" which is a fair assessment relative to his party's wealth tax of 1 per cent on net wealth over $1 million and 2 per cent over $2 million.
He also referred to his party's tax policy as a "top priority" rather than a "bottom line."
But both Robertson and Shaw hardened their messaging the following day.
For Robertson, when asked if he would rule out implementing the Greens tax policy, he said "Yes" - although the qualifiers of "any" Green tax policy or "all" Green tax policy were missing so it is still not crystal clear what caveats might be implicit in his Yes.
For Shaw, he raised the prospect of the Greens sitting on the cross-benches if their policy were ignored. That is the arrangement that would give Labour enough support on confidence issues to govern if required, but otherwise negotiating everything else on a case by case basis.
He did rule out supporting a National Government.
But if you are a Labour supporter with the choice of supporting Labour or helping the Greens to survive – and that is the reality of its current state - why would you waste your vote on a party happy not to be in Government.
It is very easy to send the wrong message in the heat of a campaign when things are simplified, amplified and misinterpreted.
A previous Green co-leader, Russel Norman, inadvertently did that in 2014, when in an interview with TVNZ's Corin Dann quite close to the election he talked about greater co-operation with National – Labour did not have a hope of being in Government.
Norman's message was interpreted by some as being open to doing a deal with National and the backlash required clarification. He probably lost a few supporters from the left who heard the message but not the clarification.
The most likely outcome of Shaw's message this week was to increase the likelihood of a Labour majority Government – and that is about the only way Labour can actually keep its election promises.