Conservative Party leader Colin Craig is threatening to sue Green Party co-leader Russel Norman for defamation.
Craig says remarks made by Dr Norman at this year's Big Gay Out in Auckland have harmed his reputation.
During his speech at the event, Dr Norman said a vote for Prime Minister John Key is a vote for Colin Craig.
He then said that the thing about Craig is that he thinks a woman's place is in the kitchen and a gay man's place is in the closet.
Craig's lawyers have written to Dr Norman asking him to retract the statement and apologise.
They say it is untrue and defamatory and harms Mr Craig's reputation to say that he holds such sexist, derogatory and offensive views about women and gay men.
The Green Party says it has just received the letter and will comment later on Monday.
