High-profile Sydney doctor Kerryn Phelps has urged Wentworth voters to put the Liberal Party last after confirming she will run as an independent in the seat vacated by former prime minister Malcolm Turnbull.

Dr Phelps, a local GP, Sydney City councillor and former AMA president, announced her decision at a press conference on Sunday in the heart of the blue-ribbon, eastern suburbs seat that the Liberal Party has never lost.

She said she was prompted to stand because “the revolving door of leadership in Canberra” had weakened the standing of politicians and the major parties.

“The people here are frustrated, angry and in despair about what happened to Malcolm Turnbull.”

The independent said she was yet to organise any preferences deals but said voters should put her first and the Liberal Party last.

Dr Phelps was a prominent advocate of same-sex marriage during the plebiscite campaign.

If successful in the October 20 by-election, Dr Phelps promised not to be a destabilising presence and guaranteed not to vote against government supply bills.

Former Australian ambassador to Israel David Sharma has been pre-selected by the Liberal Party to contest the Wentworth by-election, despite Mr Morrison saying he wanted a woman candidate.

Dr Phelps said her track record as a doctor, health communicator and advocate, one of the leaders in the marriage equality campaign, author, and working mother of three gave her the skills to sit in the federal parliament.

She said her campaign for Wentworth would be a grassroots campaign by and for the people of Wentworth, much like the YES campaign for same-sex marriage.

Dr Phelps is the 11th person to join the contest. Labor’s Tim Murray and independent investment manager Licia Heath are among the more prominent candidates.

-with AAP