The latest polling has revealed an 11 point jump for Opposition Leader Mark McGowan in the preferred premier rating.
Yesterday's Newspoll shows Mr McGowan's vote now sits at 40 per cent, while the Premier Colin Barnett's approval rating has fallen by four points to 44 per cent.
WA Labor's vote on a two-party preferred basis is up by one point to 43 per cent.
The WA Liberals still hold the majority of the votes at 57 per cent.
The poll has a three per cent margin of error.