Last month two candidates - Dane Sorensen and Sandy Baraiolo - were dumped after criticising the preference deal the party cut with the Liberal Party.
"The Labor voters that wanted to vote for us they said, 'oh no we want Colin Barnett gone, ' it was all about Colin Barnett, they wanted him gone".
Will One Nation ever become a power player in Canberra?
Speaking to 2GB, federal Treasurer Scott Morrison said both the Liberal Party and Pauline Hanson's One Nation "got a message on the weekend".
Pauline Hanson has blamed One Nation's lower-than-expected result in the WA election on the party's preference deal with the Liberals, labelling it a mistake and likening Colin Barnett to spoiled milk that should have been thrown out.
The WA deal was especially controversial because the Liberals preferenced One Nation ahead of the Nationals, with whom they are not in Coalition in that state.
Even so, ABC's election analyst Antony Green points out that while One Nation polled 4.7 per cent overall, it actually managed 8.1 per cent in the seats it contested.
She said the One Nation executive would conduct a review of the campaign and how the party should allocate its preferences in the future.
"This has certainly halted the sense of momentum building around One Nation that has been there since July past year", said Associate Professor Haydon Manning, a political scientist at Flinders University.
With two-thirds of the votes counted the Australian Broadcasting Corporation forecast that One Nation would win one seat, confounding expectations that it could gain enough to influence legislation in the new state parliament. "You've just got to take your medicine on that and move forward". They put us last.
However Mr Nicholls repeated his party's commitment to preference at the next election on a seat-by-seat basis.
"She is going to get judged on her policies and she is going to get judged on her candidates", he said.
Underscoring the internal dissent, Nationals leader and Deputy Prime Minister Barnaby Joyce broke ranks and suggested the decision to ditch traditional conservative allies and swap preferences with One Nation had indeed been a factor in the defeat, leaving voters unsure who they were voting for.
"All the imbroglio with regards to preferences means people start to over-assess and exaggerate what they think the support is of their new partner and they also just confuse their constituencies", he said.
- with Matthew Knott and Fergus Hunter.