Veteran Labor senator Stephen Conroy has caught all his colleagues by surprise by resigning in a written speech tabled in parliament.
The former communications minister, described as a "Factional Dalek" by ex-minister Robert Ray, said he wanted to spend more time with his family after 20 years in parliament.
Senator Conroy was due to speak about his decision during a debate on Thursday night but decided instead to table a written copy of his 20-minute address in which he thanked his family and colleagues for their support.
"When you resent being in Canberra because you are missing your daughter's soccer training it is time to retire from the federal parliament," he said.
He said his family, including nine-year-old Isabella, had to make many sacrifices during his two decades in parliament.
It was not until 13 hours later that news broke of Senator Conroy's retirement, three months after being re-elected for six years.
Acting Labor leader Tanya Plibersek, standing in for Bill Shorten while he travels through North America on business, was not aware of the announcement when asked about it by reporters on Friday morning.
"Although Stephen Conroy's announcement came as something of a surprise to me, in another sense it is no surprise at all - not a sitting day passes in Canberra without Stephen talking proudly of the achievements of the wife and daughter he adores," Ms Plibersek said later in a statement.
Mr Shorten, who has a Right faction alliance with the Victorian senator, said in a statement he admired and respected Senator Conroy's decision.
"He is a fiercely loyal champion of the Labor party, who has never lacked the courage to do things his own way," Mr Shorten said.
Victorian Labor's 100-member public office selection committee will meet in coming weeks to determine a replacement for the party powerbroker.
The committee is controlled by a factional alliance led by Mr Shorten, Senator Conroy and the Left's Kim Carr.
However, the next person on Labor's voting ticket at the July 2 election was former mayor of suburban Maningham Jennifer Yang, who is factionally unaligned.
Senator Conroy said the national broadband network, which began under his tenure as communications minister, had been his greatest contribution, he said.
The senator's offices were raided by federal police in May over leaks relating to the NBN.
Further raids were conducted at Parliament House in August.
The NSW Nationals criticised the way in which Senator Conroy chose to resign.
In a tweet featuring video of Ms Plibersek not being aware of the resignation, the party said: "When you haven't bothered to show up to work and everyone knows you've quit but your boss."
