Make no mistake. Prime Minister John Key will dump the Hon John Archibald Banks QSO CNZM from his ministry if circumstances so dictate.
So far, circumstances do not dictate, somewhat to Mr Key's relief.
That is because one crucial element that would force Mr Key's hand is missing from the furore over what Mr Banks knew about large donations to his unsuccessful campaign for the Auckland mayoralty in 2010.
As if merely saying so would make it happen, some media organisations this week claimed pressure was mounting for Mr Banks to be stood down as a minister while police investigate whether he broke the law.
The wider public, however, has yet to apply the necessary pressure to leave Mr Key with no choice but to strip Mr Banks of his portfolios.
The public seems relatively unbothered by the allegations.
That may be because people are not surprised Act New Zealand's leader has got himself into this mess. Mr Banks and controversy are life-long partners. And, moreover, he is now stewing nicely in that mess.
This absence of any real public pressure for Mr Banks' head appears to have persuaded the Mr Key he can tough it out and keep Mr Banks on as a minister.
That is a big gamble.
How long National can sustain the saturation coverage being given to the story is a moot point.
The collateral damage - if any - will be to Mr Key's reputation if he is seen as not displaying leadership on the matter.
But Mr Key has carefully laid out the parameters within which he will act if further revelations force him to review Mr Banks' status.
Were Kim Dotcom, for example, to produce a tape or transcript revealing that Mr Banks had phoned him to thank him for his supposedly anonymous donations, then the Epsom MP would be in deep trouble.
Mr Key will not sack him for not breaking the law. He will ditch him if it turns out Mr Banks' assurances of no wrongdoing are found to be worthless or that Mr Banks has simply misled him.
The claim Mr Key is treating Mr Banks in a more lenient fashion than he would ministers from his own party does not entirely stack up.
The resignations of Nick Smith and Phil Heatley followed clear errors of judgement on their part. Richard Worth' s departure - though never fully explained - seems to have been a clear breach of the standards expected of a minister. The claim of inconsistency might apply in the case of Pansy Wong. She resigned from the Cabinet prior to the evidence being produced to justify her going.
Mr Banks, however, has escaped a similar fate because he is in a very different category.
Mr Key would relieve Mr Banks of his portfolios with the utmost reluctance, not because of any personal affinity he might have with Mr Banks, but for the reason that Mr Key's priority is to avoid doing anything which might fracture or weaken National's three-way confidence and supply arrangement.
Apart from Act, that includes separate agreements with the Maori Party and Peter Dunne, the lone United Future MP.
That is essentially Mr Key's bottom-line.
National places huge stock on selling itself as the party of stable government.
If maintaining that image means sacrificing strict adherence by ministers to the highest ethical standards, then so be it. Mr Key is willing to pay the price and use up some of his political capital for National's greater good.
Barely six months into his second term as prime minister, Mr Key is not going to sit back and allow Labour the satisfaction of watching a portion of his governing arrangement disintegrate.
In renewing its confidence and supply agreements with Act and United Future, however, National has had the lingering worry that both parties are one-MP parties.
What would happen if Mr Banks or Mr Dunne fell under the proverbial bus?
In Mr Banks' case, the bus has arrived early and come perilously close to running him over. Following this week's bizarre twists and turns, who would put money on the bus not reversing right over him?
As it is, the police's track record in investigating electoral transgressions would have had Mr Banks twiddling his thumbs on Parliament's backbenches for several months had Mr Key stood him down as a minister this week.
Mr Banks would still have cast Act's single party vote in National's favour.
Not to do so would fly against his own party's principles as well as incurring the wrath of Epsom voters.
Mr Key's job is to foresee the unforeseeable, however. Lingering in the background is the fear that - as has often been the case with demoted MPs - Mr Banks might go feral on National and start voting against the Government.
The possibility, however small, can never be ruled out. So why take the risk?
More so given Mr Banks' vote is pivotal to National passing the Mixed Ownership Model Bill which paves the way to the partial privatisation of state-owned energy companies.
Were Mr Banks to find himself marooned on the backbenches, it is more likely he would resign from Parliament and force a byelection in Epsom than play the maverick.
A byelection would see the return of a National MP and the restoration of National's ability to pass measures which are not supported by the Maori Party.
It would also solve another problem. Mr Banks' behaviour over the past week is hardly going to endear him to Epsom voters come the 2014 election.
National may now have little choice but to turn off the life-support system which has kept Act in Parliament.
Act has hit absolute rock-bottom in recent polls. The likelihood of the party bringing more MPs into Parliament on Mr Banks' coat-tails would have to be rated at zero.
Act's value to National is now reduced solely to Mr Banks' vote in Parliament.
So far, Mr Key has insulated National from Mr Banks' troubles.
But Mr Key needs that vote.
Act is not just the Monty Python dead parrot.
Should there be more revelations that cast serious doubt on Mr Banks' version of events, Act risks turning into a rotting albatross.
John Armstrong is The New Zealand Herald political correspondent.
