Preselection decided in Ruddock's seat

Lawyer and think-tank executive Julian Leeser has easily won Liberal preselection for Berowra, the seat held by retiring senior party figure Philip Ruddock.

Mr Leeser, who is a former executive director of the conservative Menzies Research Centre, took out 97 of 114 votes on Saturday afternoon.

Mr Ruddock announced he would not contest the next election after he was announced as Australia's first special envoy for human rights.

"Congratulations Julian Leeser on an outstanding win in preselection for Berowra," Mr Ruddock said on Twitter.

"Now the big job begins."

Mr Leeser told AAP he was humbled and honoured to have been chosen as only the fourth Liberal to stand for the seat.

He praised Berowra's outgoing MP Philip Ruddock for his "exceptional service" to the party, community and country and said he looked forward to the campaign ahead.