Losing three West Australian Labor MPs leaves a huge hole in the party before the federal election, analysts say, and it may not have enough depth to find politicians able to sit on the front bench.
Gary Gray announced late on Tuesday he would not recontest the forthcoming poll, just days after Alannah MacTiernan and less than a month after Melissa Parke declared the same.
Political analyst David Black said there may have been pressure from party factions looking for a different spread of members and Mr Gray could have been left isolated.
"Alannah MacTiernan leaving may have been the last straw," Professor Black told AAP on Wednesday.
"Even though he got on well with the leader, he could have been squeezed out from keeping a senior role."
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Although Mr Gray survived a preselection challenge from party rivals last year, the former Rudd government minister may have felt "there wasn't really a future" in politics, Prof Black said.
John Curtin Institute of Public Policy executive director John Phillimore said he did not think the challenge was a contributing factor in Mr Gray's decision.
"It should be water under the bridge," Prof Phillimore said.
He believed Mr Gray's reasons - that it was time for a younger team that could commit 20 years in politics - and he had had a good run.
But Ms Parke's announcement was a bigger surprise, Prof Phillimore said, adding it took a toll on WA MPs to commute to Canberra.
When Ms Parke declared her intentions, she said she wanted to be closer to family and travel less.
Prof Black noted Ms MacTiernan had struggled to proceed to a senior position despite her experience and capabilities. The former state minister-turned-mayor had cited this as her main reason for not standing.
He said Mr Gray, a former Woodside executive, could find other work rather than being shunted to the sidelines in politics.
On Mr Gray's comment that Labor wouldn't win the next federal election, Prof Phillimore said the odds were against the party "but that doesn't mean it's impossible".
Now was a good time for a generational change with three seats that should remain safe, he said.
But Labor could struggle to get candidates to fill the roles and also had to get the gender balance right.
"They need to have quality people in those seats and someone who can be a minister or front bencher."
On the other hand, Prof Black said Labor was not devoid of talent but had to place the talented people in the right seats.
