At the last federal election, there was a very close exclusion which affected the final result in the WA Senate. This was compounded by the Australian Electoral Commission (AEC) losing 1400 votes. Acting as the Court of Disputed Returns, the High Court declared the 2013 WA Senate election void, and ordered a new election. This election will be held on Saturday 5 April. All six Senate positions that are normally scheduled for half-Senate elections will be up for election.
Unfortunately, no public polls have asked specifically about the WA Senate election. We have breakdowns for these polls from WA, but these polls ask people how they would vote if a general election were to be held. They are thus of limited use in predicting the result of a Senate election.
The major contenders for the WA Senate election are Labor, the Liberals, the Greens, Palmer United Party (PUP) and the Nationals. There is a remote possibility that a micro-party, such as Help End Marijuana Prohibition (HEMP) could win on favourable preference deals, but this is unlikely.
The Truth Seeker’s blog appears to have some private poll data that has PUP at about 10%, with Labor slightly down on their weak 2013 performance, the Greens well up to more than a quota (14.3%), and the Liberals well down on 2013. Polling has a tendency to overestimate the Greens and underestimate Labor; we saw this in Tasmania. In any case, if the total Labor/Green vote exceeds 42.9% (3 quotas), then three Labor/Greens will be elected. This would be up from 2 at the 2013 election. Although Labor and Greens preferences go to other left wing micro-parties before each other, it is unlikely that these other parties will do well enough to interfere with a Labor/Green preference swap.
PUP has been outspending the major parties by a massive amount, and they may threaten the Liberals for the third seat. However, the Liberal Democrats and some other right wing parties are preferencing the Liberals ahead of PUP, so it will be harder for PUP to win than at the 2013 election.
I believe that the most likely scenario is for the Liberals to win three seats, Labor two and the Greens one. There is a realistic chance that the third Liberal seat will go to either the Nationals or PUP. I think it is very likely that Labor and the Greens will win three combined seats. Truth Seeker’s simulation method agrees with this assessment.