The Greens can expect to take a hit in the polls following their tumultuous week.

Pollster Stephen Mills says the Greens have always had supporters who believe they're in politics for the cause - and not the perks of being an MP.

He said this last week has probably seen those beliefs disappear, and made them look like a regular political party.

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Mr Mills told Mike Hosking that's likely to be reflected in a drop in the polls.

"I'd say they'd be bracing themselves for a reasonably big fall from the 14's to 15's they were recording before," he said.

"New Zealand voters always seem to punish disunity, and I think it's quite unexpected from the Greens as well, part of their brand is idealism."

LISTEN TO THE FULL INTERVIEW WITH STEPHEN MILLS ABOVE