More than 500,000 people are casting their votes in five by-elections around Australia but some results may not be known for some time and two seats are set to go down to the wire.

The seats of Longman and Braddon are the tightest of the five Super Saturday by-elections and both electorates have seen concerted campaigning by both Prime Minister Malcolm Turnbull and Opposition Leader Bill Shorten.

Mr Turnbull visited the north Brisbane seat of Longman on Friday securing last minute support for LNP candidate Trevor Ruthenberg and on Saturday was alongside Brett Whitely in Tasmania, who held Braddon before losing the seat to Labor’s Justine Keay in 2016.

And while Labor leader Bill Shorten went missing on the eve of the by-elections, he also appeared in the tightly contested northern Tasmanian seat of Braddon on Saturday morning.

Voters showing up to vote early at Nixon St School in Devonport were confronted by both Mr Turnbull and Mr Shorten as the race for the crucial seat neared the finishing line.

The government has hopes of regaining the seat it lost to Ms Keay,
Ms Keay, who was forced to step down in May when it was revealed she had not renounced her British citizenship. The latest Newspoll, published in Saturday’s The Weekend Australian newspaper, has Labor ahead 51-49.

The Liberals’ Brett Whiteley, who held Braddon before Ms Keay, is trying to stop her return but can’t vote for himself as he lives outside the electorate.

“What’s best for Braddon? Best to have Brett Whiteley in the House of Representatives, a loud, strong voice in the party room of the coalition as I always was,”‘ Mr Whitely said on Saturday, standing alongside the prime minister.

Ms Keay, whose campaign has been bolstered by a steady stream of senior Labor politicians, said Labor was in touch with the needs of Tasmanians.

“This shows the people of Braddon we are committed to this electorate, the Labor Party, unlike Malcolm Turnbull who comes in for a fleeting visit when it suits him,” she said on Saturday.

By-elections billed as popularity tests for leaders

Apart from deciding the electorate’s next MP, the by-election is being billed as a test of Mr Turnbull’s and Mr Shorten’s popularity.

Both have made many trips to Braddon during the nine-week election campaign trying to woo voters.

Labor has campaigned heavily on improving health, while the Liberals say only they can create jobs and boost business in the region.

Preferences from independent and outspoken fisherman Craig Garland and the Greens could push Labor across the line.

A victory would be historic for the Liberals – a government hasn’t won an opposition seat at a by-election for 98 years.

Polling booths opened at 8am and will close at 6pm when counting will start in the closely watched seat.

Longman result may not be known for several days

Meanwhile, the LNP’s Mr Ruthenberg, standing alongside Home Affairs Minister Peter Dutton handing out hand-to-vote cards may have to wait several days for a result.

The newspoll in The Weekend Australian has Labor’s Susan Lamb ahead of him 51-49.

“I think it’s going to be sometime till we see a result. It’s that tight,” Mr Ruthenberg said while handing out how-to-vote cards alongside Home Affairs Minister Peter Dutton.

At one stage Mr Ruthenberg was heckled over the recent scandal about his military medals. He aid he didn’t think the fuss over his military medal would effect the vote because he had owned up to the error.

“The community has accepted that apology. It would be nice if Susan Lamb stuck her hand up and accepted the fact we are even here today because she lied to the parliament.”

"Where's your medal!" Labor supporters heckle LNP candidate 'Big Trev' Ruthenberg handing out with @PeterDutton_MP in #longman. Minister says they're "union thugs" and "actually turn voters off" #auspol @SBSNews pic.twitter.com/erwvqcVxps

— Brett Mason (@BrettMasonNews) July 28, 2018

The Newspoll shows the LNP could only win if it secures 80 per cent of One Nation preferences.

Speaking to reporters on Saturday in Braddon, Mr Turnbull said Labor was struggling in the Super Saturday by-elections because of their dishonest campaigning in Longman and Braddon.

“I don’t normally get into political commentary but let’s be fair dinkum about it, Labor should be miles ahead,” he said.

“These are by-elections. By-elections invariably swing against the government of the day.”

If the LNP does win, it would be historic. A government has not won an opposition seat at a by-election since 1920.