An emotional former Opposition leader Brendan Nelson says he has "mixed feelings" about leaving Parliament at the end of next month.



His decision means there will be a byelection in his safe Sydney north shore seat of Bradfield, which is a potential problem for Opposition Leader Malcolm Turnbull.

Dr Brendan Nelson ... set to announce he will leave Parliament before the next election.

Dr Nelson lost the leadership to Mr Turnbull in September last year and, in February, he said he would leave politics at the next election.

This afternoon he told reporters outside his office in Lindfield, on Sydney's north shore, that it had become obvious to him that his seat needed a "new, energetic representative sooner rather than later.