Stephen Smith is worried about voter turnout for the WA Senate election if numbers at one polling booth are anything to go by.

Low voter turnout at a central Perth polling booth is a worrying sign, Labor’s former defence minister Stephen Smith says.

The Australian Electoral Commission said pre-poll votes and postal votes had been stronger than for September’s federal election.

But Mr Smith, who was the deputy booth captain at Mount Lawley Primary School, said he had seen voters trickle through.

He said 1300-1400 votes had been cast at the booth by about 2pm (WST) at the last election, compared to 750 on Saturday.

“I am a bit worried, I have to say, worried about a low turnout,” Mr Smith told reporters.

“It’s been a bit of a trickle. A low turnout hurts Labor most.

“It’s the single biggest danger to Labor not getting two senators.”

He said he’d also noticed fewer how-to-vote cards being taken up.

“That says to me there’ll be a lot of people who will vote under the line. It also means, I think, a lot of people have come to the polling booth having made their mind up.”

Mr Smith said he didn’t think the micro parties would do well, although Palmer United Party posed a threat to the Liberals, possibly taking one of the three seats it was hoping for. If so, it would be the first time in about 25 years the party only won two seats in the WA Senate.

That would be a heavy blow to the party, he said. He also said expected Labor would win two seats – declining to comment about Joe Bullock’s negative comments about his running mate Louise Pratt – and tipped Greens Senator Scott Ludlam would keep his seat.

“That, I think would be a not surprising outcome. Time will tell”.

Senator Ludlam said his campaign had involved the largest volunteer effort he had seen in his time with the party, with more than 35,000 phone calls made and tens of thousands of doors knocked.

“I think it’s an expression of the way people are feeling about the Abbott government and their performance and their aggression in the last seven months, and the way that people are coming to realise the Greens are the ones with the plans for the 21st century,” he said.

“Even though we’ve had to do this twice and it is unprecedented, it’s given Western Australians… a unique opportunity to cast their judgment on the Abbott government.”

He said the stakes were extremely high, with matters such as the future of the Clean Energy Finance Corporation hanging by one vote.

Prime Minister Tony Abbott made a last-ditch plea to WA voters before jetting out of the country to Asia, releasing a recorded message saying Labor and the Greens 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 are “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.