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.
List of Australian Senate appointments
Replacement senators for the Australian Capital Territory or the Northern Territory are chosen by the relevant territory legislature, under s.44 of the "Commonwealth Electoral Act 1918". Where the legislature is not in session, the choice is made by the Chief Minister of the ACT or the Administrator of the NT. Prior to the passage of this legislation, replacement territory senators were chosen by a joint sitting of both houses of the Federal Parliament, under s.9 of the "Senate (Representation of Territories) Act 1973".