That gives Peters choice and power as the person who may decide whether Key or Labour leader David Cunliffe is the next Prime Minister.
You can almost hear the sunshine in his voice as he chats away from his home in Auckland, with not a hint of irritation at the lawnmower blaring away nearby.
Peters is in a good mood at the end of his summer holiday. He did a bit of fishing - snapper, tarakihi, porae and flounder - had a few picnics, watched a few Black Caps victories and made what has become a regular journey south to the Kumara races on the West Coast, in the name of history, as well as a fine day out.
"It has become an icon event since they were going to shut it down in the mid-70s," he says. "Muldoon stepped in to keep it going and it went from being just another race meeting to something they had to preserve."
It is no casual day out. He honours the occasion with a suit and tie.
"You can always take your coat off but you can't put it on if you haven't got it."
Key takes the same approach. It's better to approach the election with options to work with than to find yourself with just the shirt on your back afterwards.
Peters' view of what happened on Tuesday differs to many other observers'. Not surprisingly he disputes that Key has given him relevance. His own record over 20 years on issues such as "the defence of retired people of this country" did that.
And he does not embrace the title of "kingmaker" even though that's what Key's big shift in position may make him.
"It images an obsession with the political machinations of political parties, not the purpose of politics," he says.
He finds it bizarre that larger parties are helping to construct smaller parties, evidenced most recently by National taking an active interest in who becomes Act leader, or Key talking up the potential of the Conservative Party.
"It's all so conveniently expedient. Frankly we don't want to be tarnished by the process."
If there is one thing Peters hates talking about, it's other parties - especially the Conservatives, whom he accuses of theft.
"Trawling through New Zealand First's policies and my speeches in an attempt to construct a political party is not going to work. Look through their manifesto. It's just a wholesale steal."
He is not actually critical of the Greens this day but refuses to talk about post-election positions and specifically whether he would replicate his 2005 position.
Then, he refused to give support to Labour if it were in coalition with the Greens (the same promise was made for National and Act). He effectively kept the Greens out of Government and the party for the third successive election was forced to simply support a minority Labour Government, with no place around the cabinet table.
"What I can tell you now," says Peters, "is that New Zealand First is not going to waste one second considering these permutations before election night.
"We are adamant that we are not going to get reined into screeds and screeds of columns of speculation. We are going to get on with the job and maximise our vote."
He can see no point in overly co-operating with other opposition parties for the same reason. "We are all in this political market to get our share of the vote and I think there is something slightly bizarre about departing from that objective and having talks with others."
He has not had formal talks with new Labour leader David Cunliffe, or any other leader, besides a meeting with Mana Party leader Hone Harawira about what Peters called a serious medical matter for Maoridom.
"My view was when it comes to prostate cancer where there is a crisis in the Maori world, if there isn't in the non-Maori world, but there is a crisis and we have got to put our politics aside and try to deal with them now."
His positive view of addressing a Maori health crisis stands in contrast to one of his strongest policy platforms, opposing anything he terms as "legal apartheid", including the Maori Party's flagship whanau ora social service system.
"Social welfare will be delivered on race-based lines which is outrageous," he says.
So is he saying he could not be part of a Government that continued such a policy?
"Exactly."
That may not be as definitive as it sounds. When Peters became Foreign Minister in Labour's 2005 Government, he insisted he was not part of Government because his party was not in coalition.
National believes it may get a headstart if New Zealand First turns out to be kingmaker because of its position since 2005 to deal first with the party with the highest number of votes.
Peters made an important speech on coalitions before the 2005 election, although it and Peters' ensuing press conference led to much debate and several interpretations.
In that speech, Peters said it was a "constitutional convention" to deal with the biggest party first.
This week he confirmed it but did not attach great weight to it.
"It's really a position about process," he said.
"If, for example, you were contemplating talking to a party with the largest vote that wished to nuclearise New Zealand in power and defence issues, then I don't think the conversation would start. All things being equal, you would talk in the first instance to the party with the largest vote."
Peters turns 69 this year. He laughs at a claim by former Act leader Richard Prebble in the Listener that he has "lost his mojo".
"He never admitted I ever had one," he says. "Frankly I think people get tired of former politicians who ended up as a failure in their political career giving their present views. I'm afraid all of us are victimised by having to endure it but I would have thought when you vacate the scene, leave it vacated."
So why didn't he do the same when he was voted out of Parliament in 2008 after donations scandals including an undeclared $100,000 donation for Peters' legal fees by Sir Owen Glenn.
"I wanted to come back because I knew we had been most foully treated and I was never going to settle for that destiny."
Peters has been Treasurer and Foreign Minister in various Governments but says he is not thinking about post-election jobs. The best way to go into the election was to want for nothing personally or for your caucus in terms of political preferment.
"Politics is filled with people who want to be something. Well I've been there and done that. What I want to be is the leader of a political movement that is seriously strong at the end of election night 2014. That is going to be our only objective."
Record on coalitions
• 1996: Refused to give a preference before the election but NZ First's 17 MPs held the balance of power after the election and entered formal majority coalition with National.
• 1999: Barely scraped back into Parliament with four MPs. Not required with Labour and the Alliance having the Greens' support to govern.
• 2002: Back with 13 MPs but not required as Labour and the Progressives had support from United Future and the Greens.
• 2005: Pledged not to oppose highest polling party, Labour or National, from governing but only on basis that they were not in coalition with the Greens or Act respectively. Returned with seven MPs. Backed Labour minority Government. Peters became Foreign Minister, outside Cabinet.
• 2008: Not returned to Parliament.
• 2011: Pledged it would not support any party on confidence and supply and stuck to that when returned to Parliament with eight MPs.
