Malcolm and Lucy Turnbull have joined John Howard by weighing in to the Wentworth preselection battle and urging Australia's former ambassador to Israel Dave Sharma to stay in the race, putting them at odds with the Prime Minister.

The Turnbulls have thrown their support behind Mr Sharma, calling him from New York to tell him to stay in the preselection race, despite Scott Morrison insisting that a woman contest the seat of Wentworth.

Malcolm and Lucy Turnbull have told David Sharma they will support his preselection. Credit:Andrew Meares

Mr Turnbull told Mr Sharma that he should contest the preselection on Thursday night and he would have the former Wentworth MP's full support during the campaign.

The Turnbulls' intervention follows former prime minister and party elder in Mr Howard telling Mr Sharma that he should not withdraw from the Liberal preselection battle on Thursday night.