Prime Minister Tony Abbott made a last-ditch plea to West Australian voters as they headed to the polls for a Senate election re-run today.
West Australians have visited more than 700 polling booths around the State amid speculation that participation could be low because of voter fatigue.
Voters will elect six senators from 77 candidates, with the coalition, Labor, the Australian Greens, Palmer United Party and a raft of micro parties fighting for seats.
There are 738 polling places open until 6pm.
It is the third election in WA in just over a year after a State election in March last year and the September federal election; not including local government elections.
The re-run Senate election will be a referendum on the first half year of Mr Abbott's reign, but will also prove the biggest test yet for the nation's electoral commission.
Before jetting out of the country to Asia on Saturday, Mr Abbott recorded a message saying Labor and the Australian Greens in the Senate were standing in the way of his government's plan to repeal the mining tax and carbon tax.
"If you want to get rid of these anti-West Australian taxes . . . that means voting Liberal," Mr Abbott said.
He said coalition candidates were "absolutely committed" to scrapping the taxes and the Government hoped to get the numbers in the upper house from July to pass the repeal legislation.
"Send a strong message to Canberra, send a strong message to the Labor Party," Mr Abbott said.
"You can't say one thing in Perth and do the opposite in Canberra.
"That's my plea."
The Liberals pounced on Labor's lead candidate Joe Bullock's reported comment that running mate Louise Pratt - who he shunted to second on Labor's ticket - was a "poster child for the left", saying it pointed to disunity and dysfunction in the party.
Media reports today suggested Ms Pratt defied her party's recommendations on her ballot paper and voted below the line in front of the media at Dianella Heights Primary School.
Mr Abbott said the outcome of today's election was important for Australia's future, with some candidates concerned that a lack of interest could benefit minor and micro parties.
But the Australian Electoral Commission's Phil Diak said voter fatigue did not appear to be a problem, judging by the number of early votes submitted in the lead-up to polling day.
At the September election, WA had the lowest voter turnout in the country.
Voter numbers have increased by 28,000 since the previous poll, bringing the total number of registered voters to 1.48 million.
A fresh senate election was ordered in WA and an official inquiry launched after the AEC lost 1370 votes during a recount.
The AEC was further criticised this week when 75 votes at an aged-care facility were declared invalid because a ballot box was not properly secured.
The AEC admitted the pre-poll votes at the RAAFA Estate retirement home in Merriwa were put in an unsecured box and then transferred to a secure box in breach of proper procedure.
The votes were declared invalid and the retirement home's elderly residents had to recast them on Friday.
One of the residents said she hadn't even put her vote in a box and it had instead been taken by "the lady".
Both sides of politics were troubled to hear of the latest controversy to dog the AEC, which was lashed by former police commissioner Mick Keelty after his investigation into the missing ballot papers.
The AEC's harshest critic, Clive Palmer, called for more heads to roll, after two key AEC staffers resigned over the last debacle, and even called for a royal commission.
Mr Keelty found fault with just about every aspect of the AEC's handling of the second count, but the commission said on February 28 that it had implemented key practical recommendations of his probe.
But two days before West Australians marched back to the polls for the fourth time in just over a year, those reassurances were a distant memory as news of yet another ballot box blunder emerged, leaving confidence in the AEC shattered.
Prime Minister Tony Abbott, who has not held back in his disdain for the AEC's "ineptitude", said Australians had a right to expect there would be no errors this time around.
Mr Diak said every step would be taken to minimise the chance of mistakes.