Missing ballot papers and micro-party candidates being pole vaulted into the Senate will dominate a parliamentary inquiry into the conduct of the 2013 federal election.
Australian Electoral Commission officials will face a grilling by the joint standing committee on electoral matters in Canberra on Thursday.
Committee chair Tony Smith said the missing ballots in Western Australia, as a result of a "smorgasbord of flaws" by the AEC, had left the voting public dumbfounded.
"The loss of 1370 ballots in the WA Senate election is the biggest known failure by the AEC in living memory," he said in a statement.
Acting Electoral Commissioner Tom Rogers and the Australian National Audit Office will give evidence on the lost papers on Thursday.
On Friday the focus will shift to Senate voting practices.
"That our above-the-line Senate voting system can pole vault - almost randomly - a micro party candidate with a primary vote no larger than a typical suburb, into the Senate, as a result of tactical preference swapping is, I think, for most Australians, baffling," Mr Smith said.
The ABC's highly-regarded election analyst Antony Green will appear at the hearing.