Listen here: Andrew Little - I'm in this fight
"It's an inevitable question that comes up. I'm the type of guy who does take responsibility."
He added: "I felt honour bound to raise that as a valid option."
Now that he had his caucus' backing, he said he would "stepping up" his campaign and "spending even more time" on the road over the next two months than initially planned.
"I'm in this fight. And I'm going at it hammer and tongs because there is too much at stake for far too many New Zealanders."
Asked whether 24 per cent was Labour's low point, Little said "it better be". "I'm not planning on an alternative, I'm getting absolutely stuck into the campaign that we've got."
Prime Minister Bill English did not celebrate the new poll, saying that his party could still lose the election despite Little and Labour's woes.
"Even with the Labour Party doing badly, the Greens on their policy problems over welfare, and NZ First promising everything to everybody, they could form a government," he told Newstalk ZB.
"On that poll last night, the Government could lose the election. So we've got a lot of hard work to do over the next two months because we have to get our support up."
He warned National supporters against complacency, repeatedly saying that National needed to lift its vote if it wanted a "strong, stable government" which did not depend on New Zealand First.
English rejected suggestions that NZ First could overtake Labour, saying that Labour remained a "strong brand".