The Prime Minister is set to suffer another blow with Liberal MP Ann Sudmalis set to announce she won't re-contest her seat at the next election.

It was only four months ago, she stood shoulder-to-shoulder with Scott Morrison in her electorate as she battled to hang on in a pre-selection fight.

The now-Prime Minister backed her then, saying publicly "I think it would be a bad thing for the Government if Ann Sudmalis was replaced by any other candidate."

The Prime Minister is set to suffer another blow with Liberal MP Ann Sudmalis set to announce she won't re-contest her seat at the next election. (AAP)

The south-coast electorate of Gilmore is marginal, Ms Sudmalis holding it by just 0.7 percent at the 2016 election. (AAP)

The south-coast electorate of Gilmore is marginal, Ms Sudmalis holding it by just 0.7 percent at the 2016 election.

Her decision to walk away from politics, would be another blow for the Prime Minister, 48 hours after Katherine O'Regan, his preferred choice to replace Malcolm Turnbull in Wentworth, was defeated by a man.

The government has also been hit with claims of a culture of bullying.

It was only four months ago, she stood shoulder-to-shoulder with Scott Morrison in her electorate as she battled to hang on in a pre-selection fight. (9news)

And several female Liberal MPs have backed calls for change, to increase the number of women within the party.

Some have suggested targets, others, like Julia Banks have publicly called for quotas.

The Prime Minister said yesterday he has always preferred the merit system, of the best people for the job, being selected.

The south-coast electorate of Gilmore is marginal, Ms Sudmalis holding it by just 0.7 percent at the 2016 election. (9news)

Ms Sudmalis will not force a by-election in her seat and will stay on until the next election,

The two-term MP says her biggest concern now is battling to help dairy farmers,

"I've got 5th generation dairy farmers who are likely to be walking off their land at Christmas if we can't change the farmgate price for milk.”

"I'd like to see Coles, Woolies, Aldi and IGA increase their retail price and put that all back to the farmer."