Andrew Little says Labour would need a considerably greater share of the vote to form a government than the latest polling of 24 percent.
Mr Little revealed yesterday he offered to step down as Labour leader following the party's lowest ever poll result.
He said his colleagues had rejected his offer to step aside following the One News Colmar Brunton poll, which dropped Labour to 24 percent, but had the allied Green Party at 15 percent.
Mr Little speaks to Morning Report live in the Wellington studio:
The Green result was that party's highest ever in the Colmar Brunton polls, and the party said it would return 18 MPs to Parliament.
Mr Little said stepping down had to be an option he considered.
"I didn't offer to resign [but] in discussing the poll and looking at and considering it, I said that must be an option - that must be a valid option - because I think that is the responsible role to take."
He said he was "absolutely determined" to be the Labour leader, and it was an honourable thing to consider standing down.
"I wouldn't be doing my duty as leader to the party and acting in best interest of the party not to flag that with them."
He would not discuss the detail of the conversations with his senior party colleagues, but said he had talked to them about speaking publicly about the move.
"I indicated that, 'Look, there's going to be interviews about this and I have to be in a position of being very clear,'" he said.
Asked why he had raised the subject in the media, he said he was not playing the political games others were.
However, he was not giving up.
"I have made it very clear to colleagues that I am absolutely and utterly determined to fight.
"We cannot be a country that shuts so many out of home ownership, that shuts so many out of a home at all with the level of homelessness that we've got, that runs down our health services that leaves so many people out of work and with a government that claims we are an economic success."
He was realistic about what the low polling meant for the party's chances in the election, however.
"Let's focus on the challenge that is facing Labour and me right now. We have another poll result that has gone down since the last time.
"At 24 [percent] you don't get to form a government, that's just a reality."
Labour's share of the vote would have to be "considerably greater" than 24 percent to do so, he said.
The Green Party and Labour have a memorandum of understanding which means they will work together to change the government.
On Green co-leader Metiria Turei's decision two weeks ago to reveal she had lied to Work and Income, Mr Little said he thought the way the Greens took up the issue was not helping to grow the centre-left.
Mrs Turei told Morning Report her party was still committed to working with Labour to change the government despite the party's recent poor polling.
"We're committed to changing the government with Labour. We are still committed to doing that, that is still entirely on the cards," she said.
"The polls show that Labour and the Greens and New Zealand First could take government on 23 September.
"Now, we all need to do better and we all need to grow our vote, there's no doubt about that."