Former Green Party leadership candidate Vernon Tava has been tipped to stand for National in the Northcote seat.
National has opened nominations for candidates to contest the by-election after the seat was vacated by Jonathan Coleman.
The nominee is set to be announced on April 15, but The AM Show host Duncan Garner thinks he knows who the frontrunner is.
"I think Vernon Tava is an impressive guy," he said on Thursday.
"He has put forward his name, he is nominated, for the by-election. He wants to win the seat. He is going to replace Jonathan Coleman. He's going to be the guy that stands for National - I think - in Northcote. No one else has put their name forward."
Mr Tava stood as the Green Party candidate in Northcote in the 2011 General Election. But he later left the party, saying it had become too socialist and moved away from its environmental focus.
- Vernon Tava: Metiria Turei's attitude proves the Greens aren't 100 percent pure
- I thought I'd joined an environmental party - ex-Green Vernon Tava
The AM Show host Mark Richardson thinks it's a great idea.
"He embodies what I would like in my National Party," he says.
"I want that green thinking, and they're very open to it. They made it very clear throughout this whole election that they are open to talking green. It's just that green weren't open to talking blue."
No date has been set for the by-election yet.