In particular, he has to alarm his opponents on the left side of politics, where the combined efforts of Labour and the Greens (according to National's internal polling) still leave them short of reaching the 45-48 per cent poll ratings Key maintains National persistently scores.
"Look, we're not a goner by any means," is the message Key is wanting to cement with voters. "I've still got options even if I currently have to rely on a few cot cases to the left and right of me to get my team over the line in Parliament."
He had a little dig at an Auckland business meeting yesterday morning which (it is fair to say) was stacked with plenty of his own fellow travellers. Many of them, as Key well knows, will also be weighing up David Cunliffe's chances as Labour leader and what cards they should play to ensure that they are well-placed if there is a change of government in late 2014.
Key will know that Cunliffe is suddenly being invited into the nation's boardrooms to give business people an indication of his own political and economic priorities.
It's exactly what happened towards the end of Helen Clark's fifth year in power when Key and then National leader Don Brash were building their platform for the 2005 election battle on the back of rising poll ratings.
Suddenly doors that have hitherto been shut start to open wider as business leaders hedge their bets and decide they had better get to know what the challenger has on offer and what it might mean for their businesses if they do happen to be the lead player in the next government.
In truth, it is an invidious position for any Prime Minister to be in.
Under the old First Past the Post system, Key's National team would have been able to pursue its own legislative agenda without having to make the at times absurd accommodations with rump parties to get sufficient votes in Parliament for a majority.
His predecessors as Prime Minister - Labour's Helen Clark and National's Dame Jenny Shipley and Jim Bolger - were also tested by MMP politics.
All had to prostrate themselves and their parties in front of lesser political players to get sufficient numbers to be in power. Something they all - apart from Shipley - proved remarkably adept at.
Key is tipping the Conservatives as a likely coalition partner or support partner for National after the 2014 election. National's internal polling shows that party is building support - particularly on Auckland's North Shore.
But Conservative leader Colin Craig is playing hard to get. Craig has indicated he doesn't want to take the inane "cup of tea" with Key that made the Prime Minister and Act's John Banks look such figures of absurdity at the 2011 election.
Key is dropping this particularly ridiculous stunt.
Surprisingly - for Craig is a Christian - he'd rather go with direct than coded messages; he'd also rather wait and see which way the cookie crumbles, or so he would have you believe before indicating a preference for either National or Labour.
Bottom line, Craig is just as likely as any minor party leader to welcome an accommodation with National if that party looks like scoring under 5 per cent on the party vote next year and needs to win an electorate seat to bring a number of MPs into Parliament.
But it's not in the Conservatives' interest either to flag that at this point.
National's current support partners are a mess.
Act's John Banks is a political cot case. His credibility has been toast since Kim Dotcom's all-too-plausible claim that Banks knew he had tossed a couple of big cheques his way at the 2010 mayoral election but failed to declare them, and he now faces a potential criminal case.
United Future's Peter Dunne still has a chance of winning Ohariu again. But the Maori Party is also damaged.
Key will be reckoning that if National can hold its support to 45 per cent (or higher) right through to the election he will be in the box seat.
New Zealand First's Winston Peters is a potential wild card.
But giving him credibility does not figure in Key's calculations at this time.
