'If I have to' - Greens co-leader James Shaw on working with Winston Peters

Green Party co-leader James Shaw says he'll work with Winston Peters if that's what it takes to change the Government.

Polls suggest while the Greens and Labour together won't have the numbers to form a coalition, if they can get the New Zealand First leader onside it's all on.

"He wouldn't be my first choice, but this is the nature of MMP and democracy," Mr Shaw told The AM Show on Thursday.

"I can [work with Mr Peters] if I have to. Ultimately, it wouldn't be my first choice."

Last year Mr Shaw and his co-leader Metiria Turei were split on whether working with the National Party was a possibility - Mr Shaw open to it, and Ms Turei "100 percent" against it.

Since then they've formed an alliance with Labour focused on removing National from Government altogether, Labour's long slump in the polls forcing them to face reality - they are highly unlikely to form a Government without the Greens.

NZ First hold the balance of power on current polling.

"If you look at the trends in the polls… it's about level pegging," says Mr Shaw. "This is a very close election."

Under Helen Clark, Labour shunned the Greens in favour of NZ First. Since then the Greens have solidified their position as the third-biggest party.

In an interview with The Spinoff in March, Ms Turei said despite Mr Peters being "annoying as hell" and holding "racist views", she admired him for his tenacity and the advice he's given her over the years.

The latest Newshub-Reid Research poll is due out Thursday afternoon.