Change of party leader: Beginning of Weatherill's first period in office: After a closely contested election in March 2010, the Rann Australian Labor Party government was returned with a majority of seats even though it won fewer first preference votes than the Liberal Party. Over the months following the election, pressure grew to replace Premier Rann in response to declining popular support of both the Labor Party and Premier Rann. At a confidential meeting in February 2011, Premier Rann agreed with senior party members to resign in March 2012 if the party agreed on a successor. During 2011, pressure mounted on Premier Rann to resign in favour of Jay Weatherill, a minister in the Rann government. An arrangement was finally struck that Rann would resign on 20 October 2011; see Michael Owen, 'Mike Rann to walk but not happy, Jay', The Australian, 9 August 2011.
Weatherill's government was commissioned on October 2011, For a survey of the political context of this change of party leader, see Haydon Manning, 'South Australia', Australian Journal of Politics and History, Australian Political Chronicle, July-December 2011, 58 (2) June 2012: 314-321 at 314-317.
Change of partisan support for premier: After the March 2014 general election for the House of Assembly, the Weatherill Australian Labor Party government lost its majority, winning only 23 of the 47 Assembly seats in the chamber. The Liberal Party won 22 seats, and two seats were won by Independents. After negotiations with the leaders of the Labor and Liberal parties, Independent member Geoff Brock agreed to support the Labor Party and become a minister in a Labor Party and Independent coalition government with a majority of 1 on the floor of the Assembly (note the difference between a coalition government and a minority government.
This change in the party composition of the parliamentary support for the premier meant that a second period in office had commenced for Weatherill (see next period in office).