Labor now has to decide who will replace veteran Victorian Senator Stephen Conroy who caught all his colleagues by surprise by quitting on Thursday night.
It was not until 13 hours later that news broke of Senator Conroy's retirement, just three months after voters of Victoria re-elected him for another six years in the upper house.
The former Labor government 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.
His retirement creates a casual Senate vacancy.
But standard practice is that such spots are filled without a by-election, unlike when members of the House of Representatives quit part-way through their term.
Victorian Labor's 100-member public office selection committee will meet in coming weeks to determine a replacement for the party's Right powerborker.
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.
