Labour leader David Cunliffe's chief of staff Wendy Brandon has resigned five months into the job, citing ill health.
Ms Brandon was a respected Auckland lawyer before taking up the role in Mr Cunliffe's office last September.
Sources said Labour's caucus and staff were told today she had resigned because of a serious case of shingles.
Ms Brandon has been on leave for several weeks because of the illness.
A spokesman for Mr Cunliffe confirmed Ms Brandon had resigned on medical advice. The resignation would be effective from the end of February.