the state parliament appoints a replacement in the event of a vacancy; in 1977 a referendum amended the Constitution to require that the person appointed must belong to the same political party (if any) as the Senator originally elected to that seat. The states with an upper house elected via STV (NSW, Victoria, and South Australia) use the same method, except for Western Australia, which holds a recount of ballots to determine the new winner, with sitting members retaining their seats.

In mixed systems