Barnett surprised by negative poll result

West Australian Premier Colin Barnett says he is a "little surprised" by a ReachTEL poll showing support for the opposition higher than for the government.

The poll questioned 1248 voters and showed Labor would smash the government if an election were held soon, with the opposition leading by 12 points on a two-party preferred basis.

The premier said on Sunday that polls were highly volatile but it seemed a year out from the election the Liberals were underdogs.

"I think it's fair to say it was a good poll for the Labor party. It was a bad poll for the Liberal Party and therefore I believe, at the moment, the Labor party's probably got its nose in front," he told reporters.

The result comes after former federal minister Stephen Smith attempted unsuccessfully to challenge Labor leader Mark McGowan for his role despite not holding a seat in state parliament.

"Just a week ago, senior people in the Labor party were saying Mark McGowan couldn't win an election," Mr Barnett said.

"A week later, some of the same people are saying he can't lose it."

The premier will announce significant changes to his cabinet after Easter and said while that alone could not ensure victory, it was important to have a refreshed cabinet heading into the election.

"Any minister that loses their place is obviously going to be disappointed. It's a tough call to make," he said.

"People that may lose their spot have all done a good job ... but it's a matter of giving others an opportunity, refreshing cabinet and changing some responsibilities."