Outlining which parties National could work with, Mr Key said he would prefer to continue working with Act, the Maori Party and United Future after this year's election but could add Colin Craig's Conservative Party.
However, he would not rule out NZ First.
"It's not like it was in 2008 and 2011 where, if he'd held the balance of power, I would have rung the leader of the Labour Party and said you're now the prime minister because we're not going to deal with the guy.
"A few things have changed since then," Mr Key said.
"It was six years ago that the particular issues around the [Owen] Glenn donation took place. We're not going to get answers to those questions but a lot of time has moved on.
"Secondly, he's been returned to the Parliament so in reality he's put that test back to the New Zealand public in 2011. If he gets back in 2014 effectively he will have been returned twice. So that puts him in a position where at least logically we should have a discussion with him."
An arrangement with NZ First was not the most likely pairing but possible. However, a range of alternatives could be formed, including National running a minority government, with NZ First abstaining on confidence and supply.
Mr Peters said National's support base in terms of minor parties was crumbling and Mr Key's comments were "a brazen attempt to manipulate the election in advance".
"We're not going to be involved in breaking down MMP or gerrymandering in an old boys' arrangement like the past. We are interested in a discussion with the public on critical issues and with our party voters and members and after that, when the people have voted, then we'll look at what we have to do."
Mr Key yesterday ruled out working with Labour, the Greens and Mana, "on the basis that there is insufficient common ground to achieve a stable and successful working relationship".
Labour leader David Cunliffe said Mr Key's announcement on potential partners was "the dance of the desperate all over again".
Mr Key's comments on NZ First were "very interesting" given he ruled Mr Peters out six years ago, saying it was a matter of principle not policy.
Mr Cunliffe said Labour could work with any other party other than National, Act or the Conservatives although any talks with Mr Dunne were very unlikely.
Possible battle lines drawn
Potential post-election partners:
National
* Act
* Maori Party
* United Future
* Colin Craig's Conservative Party
* NZ First
Labour
* Greens
* NZ First
* Maori Party
* Mana
* United Future.
