Julia Gillard's extended election campaign has suffered another damaging blow with the shock resignation of two of Labor's most senior cabinet ministers, the Attorney-General Nicola Roxon and the government's leader in the Senate, the Higher Education Minister, Chris Evans.
Ms Gillard will announce a reshuffle of her frontbench at a press conference to be held later this morning in Canberra.
Both Ms Roxon, one of Ms Gillard's closest allies, and Senator Evans, who, as Senate leader, is the third in line to the prime ministership, will quit on Saturday morning, resigning from both their cabinet posts and, in Senator Evans' case, the leadership position immediately.
He will stay in the Senate until the September 14 poll but will not contest that election.
Ms Roxon will also stay until election day but will move to the backbench.
While Ms Gillard retains the power to choose her ministers, the leadership position in the Senate will require a ballot of the ALP caucus and is likely to be hotly contested.
The current Parliamentary Secretary for Industry and Innovation, Victorian MP, Mark Dreyfus, and also a Queens Council barrister, is hotly tipped to take over as Attorney-General.
A government source told Fairfax Media that Senator Evans had wanted to leave politics and had decided now was the right time.
"He'd just had enough," the senior source said.