Labour MP Louisa Wall has come under intense pressure in her own electorate, with a large group of churches issuing a strongly worded warning to drop her bill to legalise same-sex marriage.
Twenty-five pastors from South Auckland churches signed a letter to the MP for Manurewa saying they oppose her proposed change to the Marriage Act and want it withdrawn.
"Over the last decade the Labour Party has passed laws that have weakened the family unit and angered their traditional supporters. This proposed bill would be another blow," the letter said.
The South Auckland electorates of Manurewa, Mangere and Manukau East are heartland Labour territory, and the party's MP for Mangere, Su'a William Sio, has already said he will vote against the bill.
Green Party rainbow issues spokesman Kevin Hague said MPs were dealing with a deluge of emails and letters, some of them "toxic", which warned that supporters of the bill would face repercussions at the polling booth.