Voters in John Key's Helensville electorate who oppose gay marriage are unlikely to sway him.
The Prime Minister is planning to support marriage equality when Labour MP Louisa Wall's private member's bill goes to a conscience vote.
That is despite plans to poll Helensville voters anyway.
"I'll certainly try and listen to them and factor that in," says Mr Key.
"I think on balance I think I've pretty much made the call - I'm going to vote for it."