Federal Liberal MP Ann Sudmalis has declared she is doing a "damn good job" in the face of a possible preselection challenge, as Turnbull Government ministers rally around her.

Key points: Anne Sudmalis faces challenge from real estate agent Grant Schultz in her marginal NSW seat

Anne Sudmalis faces challenge from real estate agent Grant Schultz in her marginal NSW seat Scott Morrison enthusiastically endorsed Ms Sudmalis, urging preselectors to back her

Scott Morrison enthusiastically endorsed Ms Sudmalis, urging preselectors to back her Dumping Ms Sudmalis could embarrass the PM at a time when female representation in the Coalition is a sensitive issue

The ABC understands Ms Sudmalis is facing a challenge from South Coast real estate agent Grant Schultz in her marginal New South Wales seat of Gilmore.

Prime Minister Malcolm Turnbull has labelled Ms Sudmalis a "phenomenal member" and declared she has his "strongest support".

"She is a persistent, persuasive and relentless advocate for her community," he said.

Earlier, Treasurer Scott Morrison enthusiastically endorsed Ms Sudmalis, embracing her in front of TV cameras and urging Gilmore's preselectors to back her.

"Ann has demonstrated that she is the right candidate here," Mr Morrison said.

"She has won this seat in a tough contest and if it wasn't for Ann at the last election, Bill Shorten would now be prime minister."

Ms Sudmalis made it clear she would not go down without a fight, declaring she was doing a "damn good job" in her electorate.

"There shouldn't be any reason to change the jockey on the horse," she said.

"We've got a great horse, the Government's doing a phenomenal job; why flick the jockey off?

"So that's my words to my pre-selectors."

Senior Liberals fear dumping Sudmalis would embarrass PM

A concerted campaign is underway to save Ms Sudmalis — one of relatively few women in Mr Turnbull's Government — following the shock preselection defeat of Queensland Liberal Jane Prentice.

Ms Sudmalis is considered by colleagues to be a hardworking local member but the ABC has been told she has a "poisonous relationship" with party powerbroker and NSW Liberal MP Gareth Ward, who is believed to be backing Mr Schultz.

Senior Liberals are furiously working behind the scenes to convince Mr Ward to back off, fearing that dumping Ms Sudmalis would severely embarrass the Prime Minister at a time when female representation in the Coalition is a sensitive issue.

Mrs Prentice, an assistant minister and one of just three female Queensland LNP MPs, lost her preselection to Brisbane City councillor Julian Simmonds in a grassroots vote last weekend.

It is understood Ms Sudmalis is set to receive endorsements from female frontbenchers backing her preselection, and she could be a beneficiary of a newly created "fighting fund", which has been set up to boost the number of women in the party.

Ms Sudmalis holds Gilmore by a margin of less than 1 per cent but the composition of the seat has been gradually changing, making the Liberals increasingly worried about their prospects.

The Prime Minister recently travelled to Nowra, in Ms Sudmalis' seat, to announce $155 million in funding for a new bridge, and Mr Morrison visited the electorate today.

The ABC spoke to a number of Liberals who said Ms Sudmalis would ultimately win preselection, noting she had held the seat for five years and had the advantage of incumbency.

Few believe Mr Schultz has the numbers to challenge — and predict he may end up pulling out of the race — but there is still nervousness about what will happen between now and next Friday, when nominations close.

The head of the Liberal Party's Women's Committee and former senator Helen Kroger warned the party it could not afford to go backwards when it comes to female representation, and said sitting female MPs could no longer be dumped in favour of male candidates.