Labour leader David Shearer has been put on two months' notice by his own MPs - if the poll ratings don't improve, his leadership will be challenged.
A Labour MP told 3 News today that Mr Shearer had until spring - two months away - to pick up his and Labour's performance.
The MP, speaking on condition of anonymity, said: "The caucus is just really flat. It's not panic or anxiety just yet, but a couple more bad polls and it will be. David's got a couple more months. A change in leadership cannot be ruled out before the end of the year.
"Spring time is when people will get really nervous, just over a year out from the election. We don't want to get into the "Goff-zone", where it's too late to change the leader, but you've got someone in there the public just don't want -the phone is just off the hook."
It is rare for Labour MPs to speak so openly of leadership concerns.
The MP who spoke to 3 News is not a loyal supporter of leadership rival David Cunliffe. That makes the comments more significant as it shows there are broader concerns in the caucus about Mr Shearer's performance.
Meanwhile Mr Shearer was on the by-election battlefield of Ikaroa-Rawhiti with Meka Whaitiri, Labour's candidate for the seat.
There he vowed to be the Labour leader come the next general election.