Both major parties have taken a hit in WA's Senate election re-run while the Greens and Palmer United Party are the big winners but it is the elusive sixth spot that has many on edge.
If the government's third candidate, Linda Reynolds, does not win, it will be the worst result for the Liberals in the WA senate for 25 years.
But if Labor's Louise Pratt loses, it will be a blow to the ALP, which has criticised the federal government's refusal to release its Commission of Audit report before the WA poll, which reportedly contains recommendations for savage budget cuts.
The Liberals and Labor are both hopeful of winning the final seat, despite the major parties being punished.
So far 89.61 per cent of polling places have counted first preferences, showing a 5.49 per cent swing against the Liberals and a 4.83 per cent swing against Labor.
The Liberals are expected to pick up two seats while Labor is in line for one.
The Palmer United Party (PUP) secured a 7.48 per cent swing and the Greens 6.39 per cent, which should give both parties a seat.
Phil Diak from the Australian Electoral Commission told AAP it appeared voter turnout was at about 85 per cent, with more than one million votes already counted.
Counting was limited on Sunday but will resume at 11am (WST) on Monday, he said.
Prime Minister Tony Abbott dismissed the swing against the Federal Government.
"I think it's a typical by-election result," he told reporters from Tokyo.
"Candidates who are against the carbon tax and mining tax have performed very strongly."
Mr Abbott expects both taxes to be swiftly scrapped when the new Senate takes office from July 1.
Finance Minister Mathias Cormann was not writing off the Liberals' third candidate, Linda Reynolds, for the sixth Senate seat.
"Our position will strengthen in the days and weeks ahead," he told Sky News, as counting gets underway in WA on pre-poll and postal votes.
He played down the Greens' success.
"Clearly a lot of people parked their vote with the Greens because they didn't have confidence with Bill Shorten and Labor," he said.
"They are the ultimate protest party ... Labor is at risk of being marginalised."
Senator Cormann was hopeful the Abbott government would be able to get its agenda through parliament once the balance of power moves to the cross-bench.
The government would have more options and would be working with senators from a broader range of backgrounds, he said.
Labor's shadow assistant treasurer Andrew Leigh is confident the party's second candidate Louise Pratt will get up.
He said the re-run Senate election was unusual and low voter turn-out was a challenge.
Asked how much of a factor Labor's lead candidate Joe Bullock had been in the party's poor result Mr Leigh said: "Joe's a passionate warrior for the Labor cause".
The party was forced to go on the defensive over preselecting Mr Bullock following reports of his 1996 conviction for assault, his record of voting for the Liberal party and comments that Labor could not be trusted and was full of mad members.
Mr Leigh maintained the election was fought on the Abbott government's secret cuts rather than personalities of particular candidates.
Labor’s member for Perth, Alannah MacTiernan, said it appeared some of her party’s traditional voters had backed the Greens.
Labor leader Bill Shorten said both Labor and the coalition suffered from people’s frustration in having to go back to the polls.
The result was “no endorsement” of the government, he said.
“Our goal was always to have two Labor Senators elected to stand up for WA in Canberra,” Mr Shorten said in a statement.
“There is a lot of counting to go and we’re extremely hopeful Louise will be re-elected.”
The federal government refused to release its Commission of Audit report before the WA poll which reportedly contains recommendations for savage budget cuts. WA Labor frontbencher Gary Gray said since 1990 Labor had found it increasingly difficult to win traction federally in his state.
"We peaked in many ways in 1998, when we had a strong federal Labor leader (Kim Beazley) from WA," he said.
He said Labor needed to do some soul-searching.
"Our party does need to set about the business of building itself in a new and modern WA and better relating to people in WA as a federal organisation," he said.
Foreign Minister Julie Bishop said Labor's low vote of just under 22 per cent was a "real slap in the face" for Opposition Leader Bill Shorten.
She said the Liberals were hopeful of picking up a third seat after postal and absentee votes were counted.
"From our point of view that's a very positive outcome, particularly given this is like a by-election," Ms Bishop told ABC television.
Asked if the government could work with Clive Palmer, the senior WA Liberal said: "We'll see - we haven't had to negotiate with the Palmer United Party yet."
However, she said the Coalition and PUP generally agreed on a number of measures, such as scrapping the carbon and mining taxes.
"I think we have a good opportunity to have a constructive relationship with Clive Palmer," Ms Bishop said.