Liberal women are “incredibly worried” by a potential voter backlash to the ousting of the party’s first female leader, with the high-profile figure Charlotte Mortlock giving up her membership altogether.

Just days after Sussan Ley lost the leadership, Mortlock announced on Sunday she was leaving the party and quitting Hilma’s Network – a grassroots group she established to bring “Liberal-minded women” together.

A former Coalition staffer to Andrew Bragg, Mortlock has been outspoken in pushing the party to adopt a more progressive stance on the climate crisis, and called for gender quotas to increase female representation to 50% in the party.

“I have decided the time has come for me to step down as executive director of Hilma’s Network and I have also relinquished my Liberal party membership,” Mortlock said.

“Due to recent events I have decided there are other ways I can support women and Australia.”

Mortlock said she was proud of the women Hilma’s Network had been able to support through preselections and elections, hosting events that “challenged the party to evolve”.

She was also part of a small group who brought a gender quota proposal to the New South Wales Liberal executive, to have 40% of federal seats reserved for women-only preselections. That proposal was due to be presented at the state council on 7 March but Liberal sources told Guardian Australia it had been dropped from the agenda by the management committee.

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Ley has announced she will leave parliament. Without her, just five of the 27 MPs in the Liberal party room will be women. In the Senate, 11 of 23 Liberal senators are female.

The 2022 election review, co-authored by the Liberals’ new deputy leader, Jane Hume, found the party had not addressed the concerns of female voters. It recommended a 50% “target” for female candidates and MPs over a binding quota.

One Liberal woman, who spoke to Guardian Australia on the condition of anonymity, said: “The boys are back in charge.”

She added: “We went to elections in 2022 and there were three key issues – women, the environment and integrity, and we didn’t do anything to address those issues between 2022 and 2025.

“I’m incredibly worried … here we are in 2026, and so far we’ve blown up net zero and now we think it’s a really good idea to blow up the first female leader of the party.”

Another Liberal woman, who also asked not to be identified, said: “I think the feminist faction are pretty down in the dumps.”

She told Guardian Australia that while Ley had made “some pretty big fumbles”, the former leader had not been “afforded much grace”.

“Female voters had already switched off in 2022, so I felt that they were already not listening to us,” the Liberal said.

“But anecdotally, I heard when Sussan was elected, people were a little more receptive to [her].”

The former Liberal cabinet minister Karen Andrews, who has spoken out on the lack of women and the treatment of women in the party, said there could be public backlash.

“I think it’s possible there will be some pushback from the female supporters of the party who are concerned that maybe Sussan didn’t get a fair go at the leadership,” Andrews said.

But Andrews agreed with the backers of new leader, Angus Taylor, that Ley had had enough time to prove herself.

She remained hopeful that Hume, as the co-author of the 2022 review, was “fully aware of the issues that the Liberal party has with female voters”.

“I think women will be looking to make sure that there are other women on the senior frontbench.”

In response to Mortlock’s decision to quit the party, Hume on Sunday said it was “a really sad moment”.

“Charlotte has been a great contributor and a great voice for women that hold Liberal values,” she told the ABC Insiders program.

“I think that there is real opportunity for women’s voices in the Liberal party, and it’s on us to make sure that we demonstrate to Australian women that the Liberal party is the place for them.”