Prime Minister Kevin Rudd's chief of staff has quit and will take on a job outside government.
"The prime minister's chief of staff David Epstein today tendered his resignation with the intention of taking up a new role outside the Australian government in the new year," a statement from Mr Rudd's office said.
Mr Epstein will be replaced by his deputy Alister Jordan, a long-time staffer of Mr Rudd.
His departure is the second significant loss to the Labor Party in recent weeks following the resignation of national secretary Tim Gartrell, the man who moulded last year's federal election campaign.
"I'd like to thank Kevin Rudd for allowing me the opportunity of being chief of staff to the prime minister of a federal Labor government," Mr Epstein said in the statement.
A statement from Mr Rudd said: "I would like to thank David Epstein for his hard work and loyalty as my chief of staff and principal adviser during my time as opposition leader and prime minister," Mr Rudd said.
"David's professionalism and experience were vital ingredients in establishing a new Australian government," Mr Rudd said.
"David's strong links with the business community, state governments and the labour movement were great assets during his time in my office."
With the 28-year-old Mr Jordan's move into the top job, the chief of staff to Climate Change Minister Penny Wong, David Fredericks, will move into the deputy's role.
Mr Fredericks is also a former chief of staff to the man Mr Rudd toppled for the federal Labor leadership, Kim Beazley.