Embattled federal MP Craig Thomson has left the Australian Labor Party.
Mr Thomson will hold a press conference to rannounce the move outside his electorate office in Tuggerah on the NSW central coast at midday.
It is believed Mr Thomson will move to sit on parliament's crossbench.
Mr Thomson has been the focus of claims of misuse of Health Services Union (HSU) funds during his time as its national secretary.
He is among several former and current HSU officials who are the subject of two Fair Work Australia investigations, police probes in NSW and Victoria, and an internal inquiry by former corruption buster Ian Temby QC.
Mr Thomson denies any wrongdoing during his time with the union from 2002 to 2007.