West Australian police minister Liza Harvey elected deputy premier

West Australian police minister Liza Harvey has been elected unopposed by her party colleagues as the state's deputy premier after more than a year of speculation she would be elevated to the role.

Ms Harvey will replace Kim Hames, the state health minister, who late last year announced he would step down from the deputy role ahead of retiring at the March 2017 election.

Ms Harvey, also the minister for road safety, women's interests, training and workplace development, was elected to parliament in 2008 and promoted to cabinet in 2012.