Poll has Sharkie in command in Mayo

Centre Alliance MP Rebekha Sharkie is on track to retain her South Australian seat of Mayo, based on the latest opinion poll.

The Advertiser YouGov Galaxy poll quizzed 557 voters across the electorate which stretches from the Adelaide Hills, down the Fleurieu Peninsula and across to Kangaroo Island.

It put primary support for Ms Sharkie at 43 per cent compared to 38 per cent for Liberal rival, Georgina Downer.

On a two-party preferred basis, she would retain the seat on May 18 with 57 per cent of the vote.

It's an almost identical result to last year's by-election when Ms Sharkie defeated Ms Downer with 57.5 per cent support after preferences.

The by-election was forced when Ms Sharkie came unstuck over citizenship issues.

The poll also found support for Clive Palmer's United Australia Party was just three per cent despite his campaign appearance in Adelaide last week and his local advertising blitz.