Australia's Defence Minister John Faulkner yesterday announced plans to quit the Cabinet, dealing a blow to new Prime Minister Julia Gillard as national elections loom.

The heavyweight senator said he would return to the back benches after the polls, but denied the move was prompted by last month's Labour party coup that dumped ex-leader Kevin Rudd, a close political ally.

"Inevitably some will suggest that the recent change in our party's leadership is responsible for my decision," he told reporters. "I can't say strongly enough that any such speculation is just plain wrong."

Mr Faulkner said he had always intended to step down after Labour's first term to encourage younger talent, adding that Ms Gillard had persuaded him to contest his Senate seat in the elections later this year.

"Julia Gillard has my absolute support," he said.

"I was unstinting in my efforts to see Kevin Rudd elected Prime Minister three years ago and no one will work harder than me for the government's re-election under Julia's leadership."

Mr Faulkner is the second senior Cabinet member to announce his resignation since Ms Gillard's sudden rise to power, after popular Finance Minister Lindsay Tanner said he would not contest the election.