Hundreds of police officers demanding a higher pay rise will rally outside the WA Parliament.
Officers want the government to stick to its original 1.5 per cent wage deal after breaking an election promise and announcing that all public servants' pay increases will be capped at $1000 a year.
Police union president George Tillbury said on Tuesday a 1.5 per cent increase is "not excessive by any means".
"The government needs to do the right thing by the police officers in this state, particularly with the work they're doing; it's tough conditions, they're dealing with violent people and are often getting seriously assaulted," Mr Tillbury told ABC radio.
Premier Mark McGowan will speak at the rally, where he is expected to tell officers the government cannot afford the pay rise, and other savings within the police budget will be needed to provide it.
The union has threatened to launch a third phase of industrial action on top of measures already taken that will hit the government's hip pocket, such as issuing cautions rather than fines for minor offences, but strike action is not being considered.