A ReachTEL poll of voters heading into WA's "Super Saturday" byelections shows comfortable wins for Labor, but has the Liberal Democrats out-polling the Greens in the seat of Fremantle.

The research, commissioned by Legalise Vaping Australia, put Liberal Democrat candidate John Gray on 17.4 per cent of the Fremantle primary vote, ahead of the Greens' Dorinda Cox on 16 per cent.

New polling shows comfortable wins for Josh Wilson in Fremantle and Patrick Gorman in Perth. Credit:Fairfax Media

Labor candidate Josh Wilson was ahead in the race, with the poll showing he could secure 49.3 per cent of the primary vote and 69 per cent of the two-party preferred vote.

In Perth, the poll showed Labor's Patrick Gorman leading the race with 44.9 per cent of the primary vote, ahead of the Greens on 17 per cent and the Liberal Democrats on 13.4 per cent.