Prime Minister Malcolm Turnbull has cancelled a campaign event after tensions from last year's Liberal leadership coup overshadowed his first day on the stump in western Sydney.

Lindsay MP Fiona Scott, famously lauded for her "sex appeal" by Tony Abbott during the 2013 campaign, refused to say whether she voted for Mr Turnbull in September's leadership vote when appearing with the Prime Minister in Penrith on Wednesday.

Ms Scott has come under fire recently from a prominent Abbott supporter who branded her a traitor and accused her of backing Mr Turnbull in last year's leadership battle.

"Fiona Scott only got in because Tony Abbott came out here on many visits and he made the 'sex appeal' comment," local Liberal Party member and independent councillor Marcus Cornish said earlier this week.

Ms Scott was quizzed on the comments on Wednesday.

"I take my role as a parliamentarian very, very seriously. In that, the solidarity of the partyroom is absolutely crucial," she said.

"I don't leak from the partyroom… I don't intend to start leaking from the partyroom.

"People who do choose to do those things, that's a matter for them. But for me, I hold my own moral code."

Mr Turnbull then stepped in to defend his MP.

"Fiona's spoken courageously there and, frankly, those partyroom ballots are secret ballots and they're secret for a reason," he said.

Mr Turnbull was scheduled to attend a second event in the Lindsay electorate with Ms Scott, but the remainder of the Prime Minister's Wednesday campaigning in western Sydney has now been cancelled.

The ABC understands Mr Turnbull was planning to do a shopping centre walk at the Penrith Westfield shopping centre.

Ms Scott holds the bellwether seat by a slim 3 per cent margin.

In 2013 she won the seat back from Labor, which had taken it in 2007 after the Liberal campaign was derailed by the distribution of a pamphlet linking Labor to a fake Islamic organisation.