Sir Bob Harvey has touted Chlöe Swarbrick as the obvious choice for the next Green Party co-leader.
The former Waitakere mayor and ex-Labour Party president's comments come after Green MP James Shaw announced his resignation as co-leader.
"Let's cut to the chase, it's Chlöe. It should be Chlöe. She's an extraordinary politician," Sir Bob told AM on Wednesday.
"If they don't pick her, they're crazy."
Political commentator and former ACT Party press secretary Trish Sherson said if Swarbrick gets the role, then it will be a big weight on her and co-leader Marama Davidson's shoulders.
"Because wow, that is a newbie caucus. It's the biggest caucus they've ever had… [with] nine absolutely new MPs plus they're all learning about how to now be an effective Opposition party so there will be a big weight on their shoulders," Sherson said.
Shaw has remained tight-lipped on who could be the next Green Party co-leader after he resigned following nine years in the role.
However, speaking to AM co-host Lloyd Burr on Wednesday, the former climate minister revealed he has someone in mind.
When asked if there is an heir apparent, Shaw replied:
"Yes absolutely, and I think that should be obvious to pretty much anyone. I'm not going to get drawn on who that is. It is really important that they are able to say that they are standing, that they're able to put their best foot forward."
Shaw said after his resignation speech that he wasn't going to "publicly endorse any candidate for the co-leadership".
However, number three on the Green Party list is MP Chlöe Swarbrick, who has been touted as a possible candidate for the position.
Shaw said he "doesn't see why" the party couldn't have two female co-leaders. The Green Party has a mandate that the party must have one female leader and one leader of any gender. One leader must also be Māori.
"Things are shifting and we are more embracing of gender diversity and of other ethnicities and so on than we have been in politics in previous decades," Shaw said.
"Anything could happen."
A new co-leader was expected to be announced on March 10 with nominations open from Wednesday.
