The latest 1 NEWS Colmar Brunton Poll results raise questions about what's in store for Simon Bridges as National Party leader, says 1 NEWS political editor Jessica Mutch McKay.
"When you look at the preferred Prime Minister numbers, this is the highest number for Jacinda Ardern on 51% [and] the lowest for Simon Bridges," she said, pointing out that he received just 5% support.
"There's the question of what these numbers mean for Simon Bridges' leadership.
"What I'm hearing when I'm speaking to MPs is that if he's got a four in front of the party vote, he's doing OK and can breath a small sigh of relief that the National Party vote is 40%. If it slips below that, there's more questions that are going to be asked."
In Mutch McKay's discussions with MPs, she said she has noticed a language change regarding Mr Bridges from the last few 1 NEWS Colmar Brunton Polls.
"There are small groups that are talking to each other, but we don't get the sense there is a big move at the moment," she said. "Whether the chatter around that increases after these polls numbers, we'll wait and see.
"The question for a lot of the MPs will be around stability. Are they better to stick with Simon Bridges and hope those poll numbers turn around in the coming months?"
Despite Ms Ardern's result of 51%, Sir John Key got up to 59% as preferred PM just after the Christchurch earthquakes and Helen Clark got up to 52% at the end of her first term.
The latest results midway through the Government's first term and one month after the Christchurch terrorist attacks saw Labour jump to 48%.
"There's no doubt that is a strong number," Mutch McKay said. "But what's interesting is to go back through the polling history and compare it to National - it got up to 57% under Sir John Key."
Preferred PM results:
Jacinda Ardern - 51% - (Up 7%-points)
Simon Bridges - 5% - (Down 1%-point)
Judith Collins - 5% - (Down 1%-point)
Winston Peters - 3% - (Steady)
Party vote results:
Labour Party - 48% - (Up 3%-points)
National Party - 40% - (Down 2%-points)
Green Party - 6% - (Steady)
New Zealand First - 4% - (Up 1%-point)
Act - 1% - (Steady)