Australian foreign minister Kevin Rudd has resigned after rising speculation that he would challenge the country's prime minister Julia Gillard for the leadership job she ousted him from in 2010.
Mr Rudd said in a late-night press briefing in Washington that the leadership question had affected the business of government, and that he will consult with his family and colleagues on the future.
He said that the prime minister had failed to repudiate attacks on him.
The decision follows a public spat among supporters of Ms Gillard and Mr Rudd as the government's poll ratings decline in the wake of legislation on taxes on mining, which has propelled the country's economy.
Ms Gillard (50) Australia's first female leader, has sought to refocus attention on an agenda that includes enacting "nation-changing reform" to counter climate change.
Ms Gillard toppled Mr Rudd in a party room coup in 2010. Ms Gillard's minority government is struggling to regain voter support and would be thrown from office if an election was held now.
Australia's next national election is due in 2013.
Ms Gillard said Mr Rudd never raised any of his concerns with her and did not inform her he intended to resign.
"I am disappointed that the concerns Mr Rudd has publicly expressed this evening were never personally raised with me, nor did he contact me to discuss his resignation prior to his decision," she said in a brief statement.
She made no comment on Mr Rudd's replacement, and said she would hold a media conference tomorrow.
Agencies