Newspoll shows Labor on track for WA win

Mark McGowan is firmly on track to replace Colin Barnett as West Australian premier after voter support for Pauline Hanson's One Nation in the state plummeted, the latest Newspoll shows.

The survey taken this week for The Australian shows Labor leading the Liberal-Nationals alliance by 54 per cent to 46 per cent in two-party-preferred terms.

It also showed One Nation's primary vote across WA dived from 13 per cent to 8 per cent in just six weeks.

That dip came as the party came under scrutiny for it's policies, choice of candidates and a controversial preference-swap deal with the Liberals.

Assuming a uniform swing, Labor would win 34 of the 59 seats in the lower house in Saturday's election, ending Mr Barnett's eight-year reign as premier, The Australian reported.

Mr McGowan remains the state's preferred premier over Mr Barnett by a margin of 45 per cent to 37 per cent.