Christine Forster, the sister of former prime minister Tony Abbott, will not compete for preselection in the Wentworth by-election.

Ms. Forster announced last week that she would seek run for Liberal preselection in the blue ribbon seat vacated by former PM Malcolm Turnbull.  She had been encouraged by several party members and had the backing of her brother.

But in cancelling that plan, she complained that too much attention had been "focused on the suggestion that it was a proxy for division within the Liberal party". 

Writing on social media, she assured "that is not the case, but to avoid any such perception, I will be standing aside and giving my full support to the successful candidate," adding, "I remain committed to doing everything I can to ensure we defeat Labor in the coming battles."

This leaves former Business Council of Australia executive director and same-sex marriage campaigner Andrew Bragg and Australia's former ambassador to Israel Dave Sharma as the top two candidates for the Liberals.  Labor has chosen local businessman Tim Murray.

The preselection ballot will be held on 11 September and the by-election could happen as soon as 6 October.