Western Australia Treasurer Christian Porter has shocked his state colleagues by announcing he will resign from his portfolios for a tilt at federal politics.

Mr Porter, who also holds the Attorney-General's profile, was touted as a future premier.

He is seeking Liberal pre-selection for the federal seat of Pearce and will step down immediately.

Mr Porter says he has been grappling with the decision for some time but made up his mind last weekend.

He says he has learnt a few things about himself over the last four years in politics.

He says he is most passionate about issues that are "absolutely critical to the state of Western Australia and to the entire country".

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"I've also formed the view that my greatest chance of making any kind of impact with respect to those issues is in a federal parliamentary setting," he added.

Federal Opposition Leader Tony Abbott says he is thrilled Mr Porter wants to join the federal coalition, but would not engage in speculation about whether he would put Mr Porter on the front bench.

Premier Colin Barnett says he is disappointed by the move.

"I did try to persuade him to change his mind over the weekend," he said.

"I thought he probably could have one more term in state politics."

Colleagues shocked

Mr Porter, a former senior state prosecutor, entered politics in a by-election in 2008 and became a minister within months.

Some of his colleagues have expressed shock at the decision.

Liberal backbencher John McGrath says the move has caught most party members off guard.

"I get the feeling that he might have become a bit frustrated operating at a state level where there is so much centralisation now with Canberra moving into a lot of state areas," he said.

"He probably wants to go and play in the AFL rather than the WAFL."

The State Opposition Leader Mark McGowan claims the Government is in turmoil.

"The budget is currently before the Parliament, the budget has not yet been passed by the Parliament yet the Treasurer has resigned," he said.

"That is showing a major disrespect to parliamentary process, to the state's finances, to the future of Western Australia."

Mr Porter will move to the backbench until the state election next March.

The Premier says he will temporarily take on the role of Treasurer, while senior MP Norman Moore will act as Justice Minister until permanent replacements are found.