More so than those of their competitors, National's hoardings are meant to be presidential and inspirational - even when, just occasionally, another candidate's image and name are allowed to appear alongside the PM's.
They are supposed to remind us who is in charge.
But in that respect, note the tantalising lack of a deadline. They don't say "Working for New Zealand for the next three years", nor do they say: "Working for New Zealand for at least a few months after the election", or even: "Working for New Zealand until I just can't be arsed any more."
They could have said: "Working for New Zealand until Christchurch is sorted", but no one would have believed that.
Which may explain why rumours have been circulating that the Prime Minister is not planning to stay in the job for too long after the election.
The idea is hardly a new one. After all, Key has form. He acknowledged in John Roughan's recent biography that he gave serious consideration to quitting in the 12 months after the last election.
If he'd known how much he had to look forward to, I'm sure the thought wouldn't have lasted even the nano-second it apparently did.
But that was after the election. He didn't, according to the book, go to the polls considering the opt-out option, which is what is being suggested is happening this time.
To believe Key may be planning an exit sooner rather than later suggests a level of cynicism and manipulation of the electorate that we haven't seen for, oh, several days now.
It would be to betray those who have watched him through rheumy eyes and felt themselves bathed in the glow of that charisma to the point that any negative suggestions about him and those around him have not been allowed to penetrate.
It would be to go to the polls withholding information people had a right to know, as it would have a direct bearing on their vote.
To withhold that information would effectively be to accept the criticism that the National Party is nothing without Key.
All these options are unthinkable, so it is time to put this rumour to rest and not give it a moment's more oxygen.
Of course, it would be the easiest thing in the world to ask Key his plans.
Unfortunately, given his recent history of dissembling, it would be the most difficult thing in the world to get an answer.
How was the reaction to Apple's latest launch, the Apple SmartWatch, at your place?
At mine it went like this: "Do you have to hold it up to your mouth and talk into it like a spy?"
"Spies don't actually do that, honey."
