On 23 June 2010, after meetings throughout the evening between Gillard and Prime Minister Kevin Rudd, as well as factional leaders, Rudd addressed the waiting media at 10:30 pm AEST and announced that Gillard had asked him to hold a leadership ballot in the 115-member caucus the following day to determine the leadership of the Labor Party and hence the prime ministership of Australia.
Rudd initially said he would challenge Gillard at the caucus. However, it soon became apparent that he didn't have enough support to fend off Gillard's challenge. Hours before the vote, he stood aside as leader and ended his candidacy, leaving Gillard to take the leadership unopposed. At the same caucus meeting, Treasurer Wayne Swan was elected unopposed to succeed Gillard as Labor's deputy leader, and hence Deputy Prime Minister.
Shortly afterward, Gillard was sworn in as the 27th Prime Minister of Australia by the Governor-General, Quentin Bryce, and Wayne Swan was sworn in as her deputy. The other members of Kevin Rudd's ministry, except Rudd himself, became the remaining members of the First Gillard Ministry.
Later that day, in her first press conference as Prime Minister, she said that at times the Rudd Government "went off the tracks", and "I came to the view that a good Government was losing its way". She also said that she wouldn't move into The Lodge unless she was elected Prime Minister in her own right, preferring to divide her time between a flat in Canberra and her home in Altona, a western suburb of Melbourne. She eventually moved into The Lodge on 26 September 2010.
As well as being the first woman and the first who has never been married, Gillard is the first Prime Minister since Billy Hughes (1915–1923) to have been born overseas.
In the aftermath of the leadership challenge, Bill Shorten, former trade union leader, and key Parliamentary member of the ALP Right Faction, nominated the government's handling of the insulation program; the sudden announcement of change of policy on the Carbon Pollution Reduction Scheme; and the way in which they had "introduced the debate" about the Resource Super Profits Tax as the key considerations which had led to a shift in support from Kevin Rudd to Julia Gillard as leader of the party.