The extraordinary admission from Zak Kirkup comes as disastrous polls show the Liberals could be reduced to a handful of seats at the March 13 election.
"I accept it's not my time, but I'm not going to give up fighting," Mr Kirkup told The West Australian newspaper.
I fear that we could be decimated. I fear that there could be a Labor landslide.
The 34-year-old first-term MP is seeking to reframe the election as a choice between keeping a strong opposition to provide checks and balances or allowing the Labor government to claim an unbridled "super majority" in parliament.
While not formally conceding, he said he was "sacrificing" himself and would fight hard to save as many of the Liberals' 13 lower house seats and nine upper house seats as possible.
A recent Newspoll published by The Weekend Australian showed Mark McGowan's Labor government leading 68 to 32 per cent on a two-party preferred basis.
Mr Kirkup holds his seat of Dawesville, an hour south of Perth, by just 0.8 per cent, making it the second-most marginal Liberal electorate.
He and the premier will face off in a leaders' debate on Thursday night, which now appears certain to be dominated by the Liberals' desperate bid for survival.
Early voting began on Wednesday, with the electoral commission estimating more than 15,000 votes had been cast by day's end.
Up to 70 per cent of the 1.7 million eligible West Australians are expected to vote before polling day.
The premier has consistently downplayed recent polls showing an enormous lead for Labor.
But the parlous situation facing the Liberals was underscored this week when Mr McGowan campaigned in the affluent southern Perth electorate of Bateman.
Held by a margin of 7.8 per cent, Bateman has been comfortably held by the Liberals since its creation in 2008 but is now squarely in Labor's sights.
Mr McGowan on Wednesday said he was taking nothing for granted and would use the debate to highlight his "responsible and achievable" agenda.