The major parties have officially endorsed their candidates for next month's federal Canning by-election.

Former SAS officer Andrew Hastie, 32, will stand as the Liberal Party candidate, while former Law Society of WA president Matthew Keogh will run for Labor.

The by-election, which will be held on September 19, was triggered by the sudden death of popular local Liberal member Don Randall, who held the seat with a margin of almost 12 per cent.

Mr Hastie, who today resigned his role as SAS captain to take part in the race, beat six other candidates to win the recommendation of the Liberal selection committee on Saturday and was endorsed by the party's state committee on Thursday night.

Born in the Victorian high country town of Wangaratta, he has spent much of his life in New South Wales.

He joined the military in 2001 after the September 11 terrorist attacks on the United States, and moved to WA in 2010 for his SAS training.

He was deployed to Afghanistan several times where he was involved in missions against the Taliban.

More recently he took part in operations against terrorist group Islamic State in the Middle East.

Mr Hastie also advised the Federal Government on Operation Sovereign Borders, to stop asylum seekers reaching Australia by boat.

He has been criticised by Labor for not living in the Canning electorate.

He currently lives in defence force housing in Shenton Park, close to the SAS Campbell Barracks in Swanbourne.

Prime Minister Tony Abbott, who flew into Perth today ahead of the Liberal Party state conference this weekend, said he was confident the seat would be retained by the party.

Prime Minister Tony Abbott says he is confident the Liberals will retain Canning. ( ABC News: Louise Merrillees )

"I'm confident but not complacent or cocky," he said.

"Don Randall was a tremendously popular and effective local member. He was a good bloke, he was much-loved in the area.

"I'm not saying for a moment that we're going to hold Don's margin, but nevertheless we've got a terrific candidate.

"Andrew Hastie is an outstanding individual. He's got great capacity and courage. He will certainly stand up for the people of Canning, no doubt about that."

Jobs the focus for Labor

Labor's candidate, Mr Keogh, is a dispute resolution lawyer with Herbert Smith Freehills.

In the run-up to preselection, he pushed his local credentials, having grown up in Kelmscott and Armadale, both in the electorate.

However he also does not currently live in Canning.

At 33, he is the youngest person to lead the Law Society, and formerly worked with the Commonwealth Director of Public Prosecutions.

Opposition Leader Bill Shorten launched Mr Keogh's campaign in Canning today and said Mr Keogh's family had lived in the electorate for three generations and jobs would be the focus of his campaign.

"WA has been doing it tough in very recent times after almost four decades of growth and success," Mr Shorten said.

"We all know that the mining boom has eased off and this has hit a lot of people in this community hard — fly-in fly-out workers and also people who rely upon the industry which was created through the mining boom.

"So Matt strongly and firmly believes that we need a plan for jobs in this country and a plan for jobs in Canning."

Labor candidate for Canning Matt Keogh (R) and Opposition Leader Bill Shorten say they are focused on jobs. ( ABC News: Nicolas Perpitch )

However he acknowledged it would be difficult for Labor to win the seat.

"I think that on paper it is a hard challenge, we've got a great candidate ... but on paper it is a hard challenge," Mr Shorten said.

Mr Keogh said he was honoured to have been selected.

"I've worked in this community as a youth group leader, I've worked with St John Ambulance as a volunteer," he said.

"I've worked on the board of an organisation running refuges for victims of domestic violence, and all of that work and my work as a lawyer has been around advocating for people and for helping them out.

"I want to continue doing that and I want to do that for all of the areas of Canning by being their representative in the Federal Parliament."

PUP candidate announced

Clive Palmer's Palmer United Party has announced Vimal Sharma as its candidate for Canning.

Mr Sharma is the managing director at Mr Palmer's Mineralogy resources company.

Mr Palmer, who is in Perth today, also said he would be campaigning to save the jobs of fly-in, fly-out workers in the electorate.

"I think what matters most to me in Canning is making sure that the people who are fly-in, fly-out workers from Canning, in the Pilbara, keep their job," he said.

"And under the free trade agreements we know that workers can come in from overseas and be paid the minimum wage.

"It would be disappointing if we saw foreign workers up there working for a minimum wage which undercut the market for many of the people living in Canning."

The 6,178-square-kilometre Canning electorate is in Perth's south-east.

The challenge for candidates will be to cut through to diverse voters ranging from fly-in, fly-out miners, treechangers in the Perth Hills, seachangers in Mandurah, farmers and semi-rural residents and a large proportion of unemployed or low income earners.

A Newspoll survey revealed Don Randall's 11.8 per cent margin would be wiped away and the seat left on a knife edge if the poll was held this week.

There would have been more than a 10 per cent swing, which would leave the Liberal's with a 51 per cent to 49 per cent two-party preferred lead over Labor.