Malcolm Turnbull insists the Liberal Party loss in the Western Australian election was "overwhelmingly" down to state issues and declined to rule out doing further preference deals with One Nation in the future.
WA's new Labor Premier Mark McGowan trounced Colin Barnett's two-term Liberal government on Saturday, claiming as many as 41 MPs in the 59-seat parliament.
The prime minister said Mr Barnett has made a remarkable contribution to WA and the nation, and agreed with the ousted premier the result was largely an "it's time" factor after eight-and-a-half years in power.
"He has played a great innings magnificently," Mr Turnbull told reporters in Sydney on Sunday.
Asked whether doing a preference deal with One Nation rather than the Nationals was a mistake, Mr Turnbull said this was a matter for the relevant division of the party and was entered into with the intention of maximising Liberal parliamentary representation.
"The next federal election is more than two years away and all preference divisions will be considered by the party organisation closer to an election," he said.
Opposition Leader Bill Shorten had urged the prime minister to take heed of the Liberals' huge loss in WA and rule out once-and-for-all his government doing any further deals with One Nation.
"He is is the national leader - I've ruled it out, he should do the same," he told reporters in Melbourne.
Nationals Leader Barnaby Joyce admitted the One Nation deal was a "mistake", saying it is in the Liberal Party's interest to be close with his party.
"You just have to look ... it hasn't been a good day in the office," Mr Joyce told ABC radio.
Greens Leader Richard Di Natale was more blunt, saying the clear message is Australians are "not mugs" when the Liberals do a "grubby" deal with One Nation.
"If you side up with a party that is openly racist, bigoted, short-sighted, xenophobic, economically illiterate you will be punished for it, and that's what we saw with Colin Barnett's result in WA," Senator Di Natale told Sky News.
Finance Minister and WA senator Mathias Cormann said the result was not unexpected when internal polling suggested the WA Liberals' primary vote was as low as 29 per cent and the defeat was a "long time coming".
"We will review all aspects of the campaign and the ultimate outcome and relevant judgments will be made at the right time," he told ABC television.
Labor frontbencher Mark Butler labelled Labor's WA win as "stunning" and One Nation's performance a "damp squib".
He said feedback from the WA Labor branch was the One Nation deal and the national penalty rates decision accelerated the swing away from the Liberals.
ACTU president Ged Kearney said the penalty rates factor was the "last straw" in a state where workers were feeling the pinch and more people than ever were relying on unemployment benefits.
"I think it was probably a bit of an icing on the cake type of issue for people in WA," she told Sky News.
