The battle for Pearce: who will replace Christian Porter in the Perth electorate?

If anything can be guaranteed in the Western Australian seat of Pearce, it is that whoever replaces Christian Porter, it will not be a man.

The urban fringe division that hugs the coast north of Perth has belonged to the Liberals for 33 years, with Porter holding Pearce for nearly a decade before his dramatic fall from grace.

The Labor candidate is the Wanneroo mayor, Tracey Roberts.

Roberts, Riley and Aitken all declined to speak on the record about the campaign.

William Bowe, of the Poll Bludger blog, says his money is on Labor in Pearce, with the latest Newspoll showing a 9% swing to the opposition across the state.

The seat of Pearce covers a fast-growing belt of new coastal subdivisions on the northern outskirts of Perth, home to British and African migrants and young mortgaged-up families who have to commute for up to an hour to reach the city. Further to the east is a thriving agriculture region.

A lack of rail connections, a shortage of healthcare facilities and the risk of bushfire will be key issues in the campaign.

The general manager of the Wanneroo business association, Lauren Bell, says border restrictions and a lack of backpackers have left some businesses struggling to find workers.

A significant boundary change in August deprived Pearce of all its territory outside the Perth metropolitan area.

Porter won the seat with a 3.5% swing in 2019, but announced this month he would not stand again. Earlier this year he confirmed he was the subject of a historical rape allegation against an unnamed minister published by the ABC. Porter strenuously denied the allegation and settled a defamation case against the ABC after it published a statement indicating it did not intend to suggest Porter had committed the alleged offence.

In September, Porter left the front bench after declaring he had received anonymous donations from a trust to help with his legal fees in the case, but insisted his declaration complied with the relevant rules.

Before his decision to quit, internal party polling suggested Labor was ahead in the seat.

Dr Yvonne Haigh, a public policy expert at Murdoch University, says it is crucial for the Liberals to preselect a woman, but that was no guarantee of winning.

Women make up 31% of the 151-member House of Representatives, and 53% of the 76-strong Senate, but the Liberals score worse than Labor for representation.

Martin Drum, a senior lecturer in politics at the University of Notre Dame, says with no sitting member and the Liberals beginning the preselection process late, Roberts would start favourite.

The Greens and One Nation will also stand, but any independent campaign is unlikely.