Mr Key said yesterday that National would encourage its supporters in Epsom and Ohariu to vote for the Act and United Future candidates - but a deal for the Conservatives in East Coast Bays would require National to withdraw Murray McCully, which was "a bridge too far".
Mr Key conceded the Conservatives' polling was a factor, saying a deal was a possibility a year ago "but over the course of the 12 months since there hasn't been enough movement [in the polls] there".
It means the Conservatives will need 5 per cent to get into Parliament - something leader Colin Craig said had been the plan all along, although a deal in the seat would have helped.
Mr Key ruled out any last-minute change of mind if the polls narrowed even though that decision could cost him up to three extra MPs. He said National could have other options and believed it could form a constructive relationship with NZ First despite bad blood after Mr Key ruled Mr Peters out in 2008 and 2011. He also repeated his belief that Mr Peters should set out his position before the election so his voters would know what they were voting for. Mr Peters said he had given his position in the past and was likely to do so again.
In 2011 he said six weeks before the election that NZ First would sit on the cross benches and that remained an option. However, he would not be needled by Mr Key into setting out his position before he was ready. "I'm not concerned what Mr Key says, he can do his darning and we'll keep going on with our knitting."
Watch: John Key: No clear run for Colin Craig
Labour leader David Cunliffe said the deals were blatant electoral manipulation and National was treating MMP as "a plaything" while Labour was refusing to do any pre-election deals at all. He was not surprised by Mr Key's decision in East Coast Bays, saying Mr Key had clearly realised Mr Craig was a liability.
United Future leader Peter Dunne said he was pleased with National's endorsement, but it was still up to voters to make the decision. Asked if it ruled out any possibility Mr Dunne would work with Labour again, Mr Dunne said Labour's policies and Mr Cunliffe's reference to United Future as a "spent force" had effectively done that.
"I'm someone who has a very long memory and being described the way I was by Mr Cunliffe is not something I will forget easily."
Mr Dunne resigned as a minister after he emerged as the chief suspect in the leak of a report on the GCSB but was reinstated. Mr Key said unanswered questions lingered, "but I have to move forward".
Act leader Jamie Whyte said the deal meant people who wanted to give their party vote to Act would know it would not be wasted because Act was likely to be back in Parliament. He said Epsom voters who wanted a centre-right government "understood the electoral logic".
Mr Key, an Epsom voter, said he would vote for National's candidate, Paul Goldsmith, and expected several National voters would do the same. However, others would recognise the advantage in tactical voting to ensure a centre-right government returned.
He had been as clear as he could be about National's wishes and defended the deals, saying it was a reality of MMP and it was up to voters to decide whether they believed it was worth it. He also gave the parties National has lent support to a warning not to get too bolshie - saying he did not expect to be presented with "bottom lines" before the election.
Next article: Editorial: Craig may surprise with 5%
