Barnett tight-lipped on WA deputy premier

Colin Barnett is being tight-lipped on speculation Police Minister Liza Harvey is poised to become Western Australia's deputy premier.

Ms Harvey is on leave following the death of her husband Hal, 55, after a long battle with pancreatic cancer.

She reportedly has the support of her Liberal colleagues to replace Kim Hames, who recently said he would retire from politics at the 2017 election.

The premier has told frontbenchers that they will have to take a back seat up to a year prior to the poll if they don't plan to run in the Liberals' bid for a third term in power.

"He'll still be deputy premier for a while yet but yes, there will at some stage be a new deputy premier before the next election," Mr Barnett told Fairfax radio.

The premier said he didn't have a preference for Dr Hames' replacement, but there would be a smooth transition as he had signalled his plans early.

"There will be a discussion - hopefully there will be just a broad consensus within the Liberal party as to who should take on that position.

"And can I say if someone becomes a deputy, that doesn't necessarily mean they become a leader. Julie Bishop at a federal level would be a classic example of that."