A Labour MP is telling his colleague to tell the whole truth when it comes to the gay marriage debate.
It follows comments by Mangere MP Su'a William Sio who has decided against voting for his colleague Louisa Wall's Bill.
He says it would cost Labour the next election and is against the wishes of his electorate.
Labour's Charles Chauvel says has spoken to him and says Mr Sio isn't telling the whole story.
"For every conservative person born in a pacific island and brought up there, and now living in New Zealand, there's probably four or five younger New Zealand-born people who don't see what the fuss is about."
Mr Chauvel says he respects Mr Sio's opinion.
"But when you say this Bill or that Bill's going to have electoral consequences - you really need to tell the whole truth."