Key has already publicly foreshadowed that the next general election will be held on a Saturday within the September-November period.
Convention dictates that political leaders do not make official visits during election campaigns. So, if Obama does look likely to fly across the Tasman on Air Force One, that might lead the Prime Minister and his advisers to schedule an election earlier rather than later within Key's three-month window.
There is another factor to consider. Next year, Chinese President Xi Jinping will host the Apec leaders meeting in Beijing in mid-October. It will be a significant international meeting of Asia-Pacific leaders with Key now one of the elder statesmen within the Apec family.
Again, Key being Key he will want to attend Apec, particularly if the Trans-Pacific Partnership trade deal - which is under some pressure because of the WikiLeaks' disclosure of differences on the intellectual property framework between the US and other countries including New Zealand - does get over the line.
But Key is not so star-struck that he would not depute Bill English to attend Apec (as his deputy did during the 2008 election) if he could not find a way to finesse the opportunities on the international front with his overriding desire to win the election in the first place.
There is also time to consider. The time it might take for National to negotiate a support deal with possible potential partners in a post-election environment to get a government up in the first place. Key managed to get this done in 2008 and get himself on a plane in time to make the Peru Apec days after that election.
But this time around the game will be tougher as David Cunliffe ups the political pressure and continues to build possible allies for Labour.
The Prime Minister is on permanent "spin patrol". Key watches the polls assiduously and watches the Labour leader even more so. He frequently gives political journalists insights into his thinking. Probably, too much of this is reported unchallenged.
But Key learnt from the master - his predecessor Helen Clark - by watching how the Labour prime minister personally drove her relationships with the parliamentary press gallery and how her insightful confidences were reported by journalists as indicating "her thinking".
This easy affability (plus the ability to put journalists on to a good lead by dropping them "the word" as Key does from time to time) is simply exploiting the opportunities that incumbency gives.
But Cunliffe must rely on leadership and sharp analysis, with the bonus of the kind of leaks that become commonplace when a government comes towards the end of its second term.
The Key spiel shapes up to a "Why put it all at risk?" scenario that goes like this: National has ensured a return to strong financial management (when many other economies are still at risk) after the global financial crisis, it has held its nerve and managed partial privatisations instead of taking on more debt, the country is in good heart despite the ravages of major earthquakes; and positive growth will kick up next year.
Cunliffe's spiel goes like this: there is too much inequality and National is complacent, embedded in "last-century thinking" and guilty of crony capitalism by cuddling up to SkyCity and Sir Peter Jackson.
Cunliffe says National is tactical and has no vision whereas Labour will drive a long-term strategy that will focus on driving a fairer deal for all and shifting the economy towards a high-tech focus.
The election fight will be a tough one - but the battleground is already being formed.
Key will be forced to come up with a few surprises of his own.
There are many factors at play and it is too early to place a bet on which politician will get to shake Obama's hand as New Zealand prime minister (that's if he does come) until well into next year.
