Australia's "fleeting love affair" with Malcolm Turnbull is almost over, according to outgoing Labor senator Joe Bullock.
Senator Bullock, who announced his premature departure on Tuesday over his party's stance on gay marriage, said Labor was in a better position than it had been at Christmas - and credited the prime minister for the resurgence.
"When the polls swung badly against Labor, it wasn't because Labor had changed, people just fell in love with Turnbull, but I think it's a fleeting love affair," Mr Bullock told AAP.
"I think they're going to turn against him and are turning against him.
"Labor's future is a little bit in the hands of Malcolm Turnbull.
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"I think that the general punter is starting to get a bit disillusioned with him - they see he's all front and no substance."
The former retail workers union boss is the fourth federal Labor MP from WA to quit this year, but said he did not believe it would affect the party's chances at the next election.
Mr Bullock said he was confident in Labor's next generation of candidates in WA, backing lawyers Tim Hammond and Matt Keogh to win the federal seats of Perth and Burt at the forthcoming poll.
The 60-year-old said he believed the election result would be too close to pick, but did not expect either side to emerge with a thumping majority.
The outspoken gay marriage opponent also ruled out a return to any form of politics with Labor or as an independent in the future.
In announcing his surprise exit on Wednesday, Mr Bullock said he was disappointed Labor voted in favour of removing the conscience vote on gay marriage after the federal election.
