Labor MPs getting out before loss: Cash

Labor MPs are getting out before they lose the next election, says Liberal frontbencher Michaelia Cash.

Former minister Gary Gray has decided not to contest the next election to enable renewal in the party, but says he thinks Labor will lose.

His decision means all three sitting Labor MPs in Western Australia won't be recontesting their seats.

"(Mr Gray's) written off the next election for Shorten and they are well and truly getting out before they lose the election," Senator Cash told reporters in Perth on Thursday.

However, she said the coalition would need to fight to win the poll.

Labor frontbencher Tony Burke said the election would be tough, but Mr Gray's pessimism was misplaced.

"Anyone who knows Gary knows his pessimism and how he often expresses himself," Mr Burke told reporters in Sydney.

"Be in no doubt, we are the underdogs."

He said that while it was hard for a first-time opposition to win back government "it's very rare for a first-term government to be as directionless as the people we have got in charge at the moment".