Barnett brushes off bruising ReachTel poll

A ReachTell poll that shows a massive 18.1 per cent swing against the WA Liberals' sitting MP for the northern suburbs seat of Joondalup has been brushed off by the premier because it was Labor-commissioned.

The poll of almost 700 residents was not only bad news for Jan Norberger, but also for WA Premier Colin Barnett and his deputy Liza Harvey, who is considered his likely successor, with respondents strongly preferring Opposition Leader Mark McGowan to lead the state.

"A secret poll, conducted by the Labor party and released to anyone who wanted it? Give us a break," Mr Barnett told reporters on Tuesday.

Mr Barnett said he believed the Liberals were campaigning well in the northern suburbs, but he expected a lot of close contests.

"Look, it's going to be tough. To get a third term is always difficult but I will present the case I think we have been a strong government," he said.