By Adam Gartrell
One of Bill Shorten's closest advisers has quit over an "unacceptable" blackface costume controversy.
Steve Michelson - responsible for the Opposition Leader's stakeholder relations - resigned "following a discussion with Mr Shorten last week", a spokesman for Mr Shorten's office confirmed on Monday.
Steve Michelson has quit Bill Shorten's office following the emergence of a picture of him with blackface.
The photo - which shows Mr Michelson in black facepaint and a curly black-haired wig - dates back to a 2007 fancy dress party but started circulating in Labor circles in recent weeks.
"This conduct - which occurred many years ago - is clearly unacceptable, and out of character for Mr Michelson, who was a valued and diligent staff member," a spokesman for Mr Shorten said.
Mr Michelson in the picture circulating among Labor figures.
Mr Michelson has worked for Mr Shorten for six years, dating back to his time as a minister in the Gillard government.
Mr Michelson, originally from Wangaratta, said the photo had been a mistake.
"I was young when this photo was taken and made a terrible decision. In the more than 10 years since then I've learnt why this type of behaviour is completely inappropriate," he said in a text message.
In an earlier Facebook post he said: "I've decided to hang up my staffer boots to spend more time with my family.
"Working with Bill Shorten and the entire Labor team has truly been a privilege however the time has come for two little kids to see a bit more of their Dad. I still passionately believe in the Labor Party and the union movement. I'm also more sure than ever before that a Shorten Labor government will do great things for everyday Australians."
Mr Michelson is a former ALP branch president and has been touted as a future federal candidate. His fall comes amid worsening factional infighting over preselection battles in the Victorian ALP.