Australia's opposition Labor party recorded impressive results in a historic series of "Super Saturday" by-elections yesterday which have raised questions about Prime Minister Malcolm Turnbull's political future.
As voting continued last night, Labor was set to retain all four of its seats which were being contested, including in two tightly-held electorates in the states of Queensland and Tasmania.
A fifth by-election in South Australia was retained by Ms Rebekha Sharkie, from the small Centre Alliance party.
The results were disappointing for the ruling Coalition and raised speculation that Labor is on track to win the next general election, which is due within a year.
The Coalition performed poorly in the contested seat in Queensland, a battleground state that could determine the outcome of the general election.
Labor leader Bill Shorten appeared triumphant last night as he addressed a raucous group of supporters in Queensland.
He had campaigned on a pledge to boost spending on education and health and has opposed Mr Turnbull's tax cuts for corporations and high-income earners.
"What a great night for the Labor party," he said. "Tonight is another signpost into the destination that matters for Australians: a Labor government after the next general election… We are going to put working-class and middle-class families at the top of the list."
The five ballots were the most byelections held in a single day in Australian history. This followed the country's dual citizenship crisis, which forced numerous MPs to leave Parliament after it emerged that they were dual citizens and therefore ineligible under the country's Constitution.
Four of the by-elections yesterday were to replace MPs who were forced to renounce their foreign citizenships and recontest their seats. A fifth replaced a Labor MP who resigned for family reasons.
Australian by-elections, which are usually held after the death or resignation of MPs, typically favour the opposition and provide an opportunity for voters to "send a message" to the government. The ruling party has not won a seat from a sitting opposition member at a byelection since 1920.
But the Coalition campaigned strongly and was hopeful of winning one of the two closely-fought seats, a development that would have placed intense pressure on Mr Shorten.
There was even speculation that a strong by-election result would prompt Mr Turnbull to call an early election.
Instead, the Coalition had a disappointing result, which will place pressure on Mr Turnbull.
Political commentator David Crowe said the result was a "dismal outcome" and would embolden Mr Turnbull's internal party-room critics.
"Sound the trumpets. Bill Shorten can expect to walk into The Lodge (the prime minister's residence) within months," he wrote in The Sydney Morning Herald.
"The results of Saturday's by-elections are a fanfare for the general election that is due by May… Another round of Coalition instability is almost certain."
The Queensland seat of Longman, which was set to be retained by Labor's Ms Susan Lamb, will be particularly worrying for the Coalition. Ms Lamb last night was on track to win by 55 to 45 per cent against the Coalition candidate, increasing her margin by about 4 per cent.
Queensland has numerous close seats that could determine the fate of the general election.
"The message for the Turnbull government is dire," wrote political commentator Simon Benson in The Australian. "Queensland has abandoned it… Nationally, it has no strategy to deal with Labor's anti-business, class-war campaign."
Labor has been consistently ahead in national opinion surveys since the 2016 election, which Mr Turnbull won only narrowly.
Mr Turnbull has faced criticism from the party's conservative wing, particularly former leader Tony Abbott, who was toppled by Mr Turnbull in 2015.
The anti-migrant One Nation party, which is led by controversial right-wing firebrand Pauline Hanson, won about 15 per cent of votes in Longman, indicating it could be a strong force at the next election.
The party is based in Queensland and tends to perform strongest there. But it typically takes votes away from the Coalition rather than Labor, which will add to the worries of Mr Turnbull.