Keenan confident of Canning win

Federal Justice Minister Michael Keenan says he's "quietly confident" the Liberals will win the Canning by-election, despite the prime minister's poor approval rating.

Speaking in Perth on Friday, Mr Keenan said the state and federal Liberal governments were coming off a high level of support from past elections and any fall in the vote could be attributed to "political gravity" rather than party problems.

"I don't envisage that we'll lose, we're fighting to win and I expect that we will," Mr Keenan said.