The WA Nationals have reacted angrily to Labor's decision to preference the Liberals ahead of them in six seats.
The Nationals fear the move could cost them up to four seats, including Warren-Blackwood, which is held by the Agriculture Minister, Terry Redman.
The party's leader Brendon Grylls says the success of the Royalties for Regions program has made the Nationals a target.
He says Labor is trying to destroy the Nationals.
"The Labor Party would rather get rid of the Nationals and just be in a Government with Liberal Party and Labor Party MPs," he said.
"It's quite clear that they've changed their strategy, that the Nationals are now the biggest target for the Labor party in country areas.
"And, that is a sign of credit to the Nationals, that we've been able to build our profile and our role in West Australian politics to that level."
The Labor Leader Mark McGowan has denied Labor is trying to destroy the Nationals.
He says the party is still preferencing the Nationals in 11 seats.
"We make judgements based upon personalities, the individual wishes of branch members in those particular electorates, but generally we're favouring the Nationals over the Liberals," he said.
The Nationals and Liberals have already announced they are swapping preferences.