Luckily for Key, whether or not that is the case will not be apparent this side of the election.
Like all trade deals it is very complicated stuff but in essence two parties can take responsibility for dragging down the deal - Australia and Japan.
Australia signed its own sub-standard bilateral deal with Japan this when compared to TPP ambitions for comprehensive elimination of tariffs by all countries over time.
With Australia having accepted second best for a short term win at the expense of long term gains, it has made easier for Japan to resist higher TPP ambitions.
Japan, a late-comer to the TPP talks, signed up knowing the other leaders had committed in Honolulu 2011 to a comprehensive deal, meaning complete elimination. It has reneged.
And while some might mumble about wanting Japan to leave the talks altogether, that would result in a reversion to US protectionist instincts in agriculture towards New Zealand. Those instincts were subsumed at the prospect of getting Japan, the third biggest economy in the world, in an FTA.
Throw in the dysfunctional nature of the US congressional politics which is in a perpetual state of campaign and fear of electoral backlash and the situation is an unholy mess.
It requires some deft leadership by the US and perhaps some inspiration by the New Zealanders.