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.
2016 Australian federal election
Labor Senator Joe Bullock announced on 1 March 2016 that he would be resigning from the Senate after the autumn sittings of parliament, citing—among other reasons—his opposition to same-sex marriage being at odds with the Labor Party's platform to bind its members in a supporting vote after 2019. Bullock tendered his resignation to Senate President Stephen Parry on 13 April 2016. The casual vacancy was filled by Pat Dodson on 28 April 2016.