JULIA GILLARD'S extended election campaign has suffered another damaging blow with the shock resignation of the third most senior minister in her government, the Higher Education Minister, Chris Evans.

Senator Evans, the government's Leader in the Senate and therefore the third in line to the prime ministership, will quit on Saturday morning, resigning from both his cabinet post and the leadership position immediately.

Had enough … Senator Chris Evans Credit:Alex Ellinghausen

He will stay in the Senate until the September 14 poll but will not contest that election.

The West Australian's departure will force a reshuffle of ministers, which is also expected to be unveiled on Saturday.