President of the Senate (Australia)
The position is provided for by Section 17 of the Constitution of Australia. The Senate elects one of its members as president at the start of each new term, or whenever the position is vacant. This is usually—though not necessarily—a member of the party or coalition that holds the most seats in the Senate. The largest party in the Senate is not always the governing party, as government is determined by the House of Representatives. The President of the Senate and the Speaker of the House of Representatives may consequently be from different parties.
Australian Senate
Senators normally serve fixed six-year terms (from 1 July to 30 June). At most federal elections, the seats of 40 of the 76 Senators (half of the 72 Senators from the six states and all four of the Senators from the territories) are contested, along with the entire House of Representatives; such an election is sometimes known as a half-Senate election. The seats of Senators elected at a half-Senate election are not contested at the next election, provided it is a half-Senate election. However, under some circumstances, the entire Senate is dissolved early, in what is known as a double dissolution. Following a double dissolution, half the Senators representing states serve terms ending on the third 30 June following the election (slightly less than three years) and the rest serve a six year term. The term of Senators representing a territory expires at the same time as there is an election for the House of Representatives.