Greens candidate for Parkes David Paull has stood down due to a Facebook post declaring he did not believe Martin Bryant was responsible for the Port Arthur massacre.
The Greens say they will take down all campaigning material in his name.
"David absolutely rejects the views he is quoted as supporting, but has stood down so that he does not become a distraction from the important issues The Greens are focused on," a spokesman for The Greens said.
Mr Paull said he does not believe that Port Arthur was a conspiracy, nor does he have any doubt that Martin Bryant was guilty of the massacre.
"I support The Greens policies on gun control 100 per cent; I was only ever interested in that Facebook group to investigate the views of Port Arthur conspiracy theorists. I made those comments after an admin asked new members to justify their presence in the group," he said.
"I am incredibly embarrassed that these posts have become public and I apologise for misrepresenting myself in this way."