The Family First candidate in the far north Queensland seat of Leichhardt says voters have a right to know the sexual preference of all candidates contesting the federal election.
A report in today's Courier-Mail newspaper says Family First's Ben Jacobsen demanded that the Liberal candidate Charlie McKillop declare if she is gay.
Mr Jacobsen, who is against gay relationships, says he was not targeting Ms McKillop, but speaking generally about every candidate.
"Look I think this is a public office, this is a person that's going to represent Leichhardt in our House of Representatives," he said.
"I think the public have a right to know the values that you're going to pursue in Parliament."
Campaigning in Cairns today, federal Treasurer Peter Costello says Mr Jacobsen's comments are unfortunate and says he is attempting to seek political advantage by raising the issue of sexual preference.
"I think upon reflection, that candidate will want to apologise for those remarks," he said.
Ms McKillop refused to comment.
Nationals candidate Ian Crossland says a person's private life should remain private.
Earlier in the campaign Mr Crossland told the media the seat was no place for a woman, a pointed reference to Ms McKillop.