Kevin Rudd was sworn in as Australian prime minister on Thursday three years and three days after he was ousted from the same job in an internal government showdown.
His office could not immediately confirm whether Rudd would replace his predecessor Julia Gillard in a visit to Indonesia that had been scheduled for next week. Gillard was dumped Wednesday by colleagues spooked by the party's dismal opinion polling.
Governor-General Quentin Bryce commissioned Rudd within half an hour of Parliament resuming for what is likely to be its last day before elections.
"I will do my absolute best," Rudd told Bryce, whom he appointed governor-general when he was last prime minister.
Anthony Albanese was sworn in as deputy prime minister and Chris Bowen was sworn in as treasurer during the same ceremony. Rudd has yet say when he will announce his complete cabinet after seven ministers resigned following Gillard's ouster.
Rudd faces a potential no-confidence vote in Parliament, which he will likely survive although a loss could trigger an election as early as Aug. 3.
Gillard tendered her resignation as prime minister Wednesday night after losing a ballot of ruling lawmakers to Rudd 57 votes to 45.
Rudd has given no indication of whether he would stick with an election date of Sept. 14 set under Gillard.
Bryce revealed she took late-night legal advice on whether she should swear in Rudd.
A minority government such as Gillard led has not been seen in Australian federal politics since World War II, and the ruling Labor Party's leadership change has raised unique constitutional questions.
While Rudd has the support of his party, he does not necessarily have the support of a majority of lawmakers in the 150-seat House of Representatives, which a prime minister must have.
Acting Solicitor-General Robert Orr wrote to Bryce that Rudd should be commissioned as prime minister.
Bryce's secretary Stephen Brady wrote that she wanted an assurance from Rudd "that he will announce his appointment at the first possible opportunity to the House of Representatives on order to give the House the opportunity for whatever, if any, action it chooses to take."
Rudd plans to make a statement on the subject to Parliament later Thursday.
Wednesday's leadership ballot was forced by government lawmakers hoping to avoid a huge defeat in upcoming elections.
Rudd had warned that Labor was facing its worst election defeat under Gillard's leadership in the 111-year history of the Australian federation.
Gillard lacked Rudd's charisma, and although many Labor lawmakers preferred her style, her deepening unpopularity among voters compelled a majority to seek a change ahead of looming elections.
Labor has depended on independents and a minor party for its fragile ruling coalition, but Rudd appeared capable of retaining it after two independent lawmakers who did not back Gillard's government said they would support his.
"In 2007, the Australian people elected me to be their prime minister and that is a task I resume today with humility, with honour and with an important sense of energy and purpose," he said Wednesday after he was elected Labor leader.