Meanwhile, Collins' refusal to answer key questions about her role in that relationship has fuelled speculation that she has something to hide.
On Wednesday morning, there was a distinct feeling around Parliament that Collins' future as a minister - she was also under pressure for her seemingly less than rapid response to the latest crisis involving her accident compensation responsibilities - might be starting to hang in the balance.
The Opposition could certainly smell their favourite commodity - blood.
But the sense of anticipation rapidly dissipated as Collins and the Prime Minister negotiated question-time in Parliament without making any gaffes.
Collins' tormentors instead let fly in the following free-for-all general debate where the word "corruption" got an extensive airing.
That Labour and New Zealand First - to use the parliamentary lexicon - were able to make so many "imputations of improper motives" against Collins was simply down to National MPs not demanding that the Speaker stop them from casting "personal reflections" against Collins.
One of Parliament's more obscure rules stipulates that if MPs believe another member is truly guilty of corruption, they must put up a notice of motion formally charging that member with impropriety.
In the interests of transparency. they are not supposed to keep slagging off that member by making veiled suggestions of corruption in debate after debate.
Such a motion would be embarrassing for Collins, particularly given her responsibilities as Justice Minister. But the motion would be voted down by National and its allies. Or, if National could not get the numbers to defeat it, it would be left to wither on the order paper, Parliament's day-to-day written agenda which the governing party controls. Or so Collins would be safe in assuming. Or would she?
What is interesting is that Collins got no help from fellow National MPs on Wednesday. Perhaps they thought she was well capable of looking after herself. But no one on National's side of the House rushed to her defence after she had left the chamber and Labour and New Zealand First started to really hammer the notion that she was guilty of a serious conflict of interest during her China trip and should resign forthwith.
Not a single National MP felt compelled to get to their feet to raise the necessary point of order to prompt Speaker David Carter, or his assistants subsequently deputising for him, to order David Cunliffe, his Labour colleague Grant Robertson and Winston Peters to desist from repeatedly declaring that Collins had been corrupt in using her status as a minister to pull rank with a senior Chinese official and oblige him to remove the Fonterra botulism scare-enforced import blockade on the goods produced by Oravida, the milk-exporting company that has Collins' husband as one of its directors.
The reluctance of her fellow National MPs to come to her aid no doubt in part reflects their annoyance that she was so silly, so unwise or so convinced of her own invincibility and infallibility that the alarm bells simply failed to ring and alert her to the obvious perception of a conflict of interest which is a definite no-no according to the Cabinet Manual and something which she now acknowledges she was guilty of.
Labour and Peters, however, are now arguing it is no longer a question of perception, it is a matter of fact that Collins' presence at an Oravida-organised dinner in Beijing was designed to persuade the Chinese official who was also a guest to lift the import freeze. Collins says the matter was never discussed. Cunliffe told Parliament it did not have to be.
Chinese culture meant the official would have got the message simply from Collins' presence - and through her husband's connection to Oravida stood to gain financially from this wielding of her ministerial mana.
As far as Collins' National colleagues are concerned, her crime is political, not financial.
The Oravida Affair has dominated the headlines for several days not just once but twice in the space of barely a month. That is not entirely Collins' fault as information has seeped out from elsewhere. But it suggests her political management skills have gone seriously skew-whiff - and at the most inconvenient time for National.
The party knows it is operating within a tiny margin when it comes to the difference between victory and defeat at September's election. Knowing it must leave some room to cater for unexpected and potentially damaging events, there is absolutely no room for avoidable stuff-ups.
Discipline is absolutely paramount. The sight of a senior front-bench minister of Collins' intelligence, capacity and calibre suddenly going off the rails in such spectacular, but mysterious fashion must be deeply worrying and troubling for John Key.
After a brief period of contrition following the exposure of her first round of questionable behaviour in connection to Oravida, she has again reverted to her trademark belligerence when it comes to staring down adversaries.
But what was previously an endearing kind of cynicism which was devastating in its impact because it also happened to be funny now more often than not sounds just like plain old jaded cynicism.
This is most apparent in her responses to questions in Parliament. This is the one forum, indeed the only forum where ministers must be accountable - otherwise the system is worthless.
Having deemed the Beijing dinner to have been a private occasion, however, Collins refuses to answer questions about what took place and the identity of and the organisation for which the Chinese official worked.
That is not only a disgrace, it is short-sighted. Sooner or later, those details will leak out elsewhere. Collins will look silly. However, the Oravida affair has obviously rocked her confidence far more than she is letting on.
That is all too apparent from her confused media strategy which earlier in the this week had her running from the media and later on - but too later on - courting news organisations to tell her side of this sorry story.
