People won't change how they vote because some spies over-stepped the mark. But the Dotcom-GCSB saga still poses a threat to the government, one it can't afford to ignore

As I've been watching politics over the years I've started building up a few rules that seem to apply regardless of party or circumstance – and with just enough exceptions to prove them. I must start writing them down! But there's one that I've been banging on about for years to anyone who will listen. And if John Key isn't careful it could start coming into play for him.

Watkin's Political Rule #1: That which they love you for in the beginning, they will hate you for by the end.

In other words, your strength becomes your weakness over time. Helen Clark's strong tough-mindedness became nanny state-control freakery. Tony Blair's charisma became smarmy. Bill Clinton's X factor became, well, X-rated.

I've written before that one of the core reasons for National's win in 2008 was that they weren't Labour; New Zealand wanted a change of shoes. Another old rule applies there: In New Zealand parties lose elections, they don't win them.

(Of course there were numerous other factors – Key's skills, the party having jettisoned some of its unpopular baggage etc. But let's not get bogged down).

Politicians are never really three dimensional in the public eye. They are defined by key attributes. Those key attributes are amplified by the spin doctors and to some extent by the media to win favour. Cometh the hour, cometh the attributes (and policies) we prefer that time, and voila, you have a winner.

But humans get bored, especially of two-dimensions. So we grow tired of the things we once admired.

John Key was anything-but Helen Clark. Warm and easy-going. Ordinary enough in his talk and manner, but extraordinary enough to be very, very rich. Relaxed and certainly no control freak or micro manager.

Back in Opposition there was the quote about him 'jumping from cloud to cloud' – a joke, but a telling one. In the early days of government he spoke of trusting his cabinet ministers to get on with their jobs and running the ship of state like a CEO; he'd only get into the details if his people screwed up.

But every coin has a flipside. The the other side of relaxed is loose.

And so we come to this week and the Government Communication Security Bureau spying debacle. The Prime Minister's own department broke the law in spying upon internet billionaire Kim Dotcom. The only public oversight of our intelligence agencies comes from the PM, the Inspector-General (whose office amounts to himself and his P.A.), and a parliamentary committee that according to sources sits little and hears less. Yet Key did not seem to bother to ask especially searching questions. And neither, for that matter, did his deputy when he was handed rare documents to sign off.

Is this a sign of Key's relaxed style starting to unravel? Remember the Tuhoe cannibalism joke? That was his relaxed nature leading him into politically dangerous territory. But a popular first-term PM can ride out such hiccoughs.

Now, not so much. Key's demeanour has seemed more weary for a while; this week he was understandably grumpy. On Close Up on Thursday he was grim. But if the charm fades, the risk is the looseness is what people will see. This is a Prime Minister who's currently refusing to read a police report that shows the story told by one of his ministers is at odds with several others, who have given statements to police.

This only matters so much. I don't think voters change how they vote because some spies trampled on the rights of a new and very rich New Zealander, however much of a folk hero he has become. The real risk for the government comes from Christchurch schools closures, job lay-offs and the like.

Another old rule: People vote from their hip pocket.

But what National needs to be wary of is losing their aura of competence. Therein lies the risk Dotcom offers. That the likeable and oh-so competent Prime Minister shows a grumpier and more bungling side of himself. His relaxedness becomes looseness, and Rule #1 starts to kick in.