As well as the whole House of Representatives, 40 of the 76 Senate seats will be up for election on May 21. There are 12 senators per state and two per territory. At half-Senate elections, six senators for each state and the four territory senators are up for election. Unless there is a double dissolution, state senators have six-year terms and territory senators have three years.
The Senate is massively malapportioned, with Tasmania having the same number of senators as New South Wales, despite the latter’s population being more than 15 times greater. This was the price for the smaller states joining the Australian federation in 1901.
For elections to the Senate, all senators up for election in a state or territory are elected by statewide proportional representation with preferences. With six senators up in each state, a quota is one-seventh of the vote, or 14.3%. With two up in each territory, a quota is one-third or 33.3%.
