During a Senate estimates hearing on Tuesday night, Australian electoral commissioner Tom Rogers told senators he had received no instructions from the government to cease preparations.

Although prime minister Malcolm Turnbull remains optimistic about the chances of the plebiscite going ahead, 40 senators have pledged to vote against it – two more than the 38 needed to block legislation.

“Experience tells me that you don’t know what the numbers are until the votes are finally counted," Turnbull said earlier this week.



Planning for the plebiscite is currently underway in the elections branch of the AEC, which consists of 40 people.

Rogers said the branch "prepares for the next election, whenever that may be" and that it is "difficult to unstitch" the specific work being done to plan the plebiscite from the general planning for the next election.

"There's a range of things we need to do," he said. "It would be the same if it was a plebiscite, an election, a referendum, another electoral event."