Key would have resigned rather than work with Winston

National Party leader John Key says he would have conceded defeat on Saturday night if the election results had shown New Zealand First holding the balance of power.

Mr Key decided before the campaign that he was not going to work with NZ First and its leader Winston Peters after the election, even if that meant staying in opposition.

He said he would not be able to trust Mr Peters and the politician was "a soap opera" who had distracted Helen Clark's Labour government.

Mr Key's decision would have left NZ First with nowhere to go except with Labour.

The party needed 5 percent of the party vote, or an electorate seat, to survive and it failed on both counts.

It gained 4.2 percent of the party vote and Mr Peters was heavily defeated in Tauranga.

Mr Key said tonight on TV One's Close Up programme that shunning NZ First had been a big call to make but he had never considered changing it.

"I made the decision that if, on election night, the balance of power was held by New Zealand First I was going to ring Helen Clark and concede," he said.

"I took the view that I would rather be a loser than a liar and I had told the New Zealand public I wasn't going to form a government with him.

"While it was pretty tight on election night I think it was the right call."