MELBOURNE -- Australia's Prime Minister Malcolm Turnbull and his Labor Party rival, Bill Shorten, face a major test of leadership months out from a national election, as voters go to the polls in key by-elections on Saturday.
Turnbull is hoping to regain momentum for his center-right government with a strong performance in the snap polls, ahead of a federal election due to take place before May 2019.
Although his personal popularity is at its highest since mid-2016, Turnbull's Liberal Party-led Coalition has trailed the opposition Labor Party in the polls for most of the last two years. In the most recent Newspoll survey released last week, the Coalition lagged its center-left rival 49% to 51%.
Despite Labor's lead, the by-elections are also seen as a major test for Shorten, whose persistently low personal approval ratings have stirred murmurs of a possible leadership challenge from within his party.
"With multiple electoral dice thrown at once, the government will be optimistic that in a couple of seats the anti-government swing may be minimal, as this will muddy the narrative of bigger swings in other seats," said Graeme Orr, a political analyst at the University of Queensland. "It even has an outside hope of a swing to it in one or two seats, possibly even winning one. That would stoke concerns inside Labor about Mr. Shorten's ability to win the next election."
Five seats are up for grabs in the "super Saturday" contest, which follows a dual-citizenship crisis that cost more than a dozen parliamentarians their seats.
Turnbull, a former lawyer and investment banker, has framed the by-elections as a referendum on the government's economic agenda of sweeping tax cuts for businesses and individuals.
"Whether it's at the by-elections or at the general election next year, Labor will be going to that election asking Australians to vote Labor and pay higher personal tax, higher business tax, higher investment tax -- well over AU$200 billion of higher taxes. And what that will mean is Labor will be standing for a weaker economy, fewer jobs and lower wages," Turnbull said in June on ABC radio.
Shorten has blasted the government's tax cuts as a giveaway to big banks and the rich, promising greater investment in health, education and other public services instead.
"We can make sure in Longman the message goes loud and clear to this government: We don't want AU$17 billion for the big banks, we want AU$17 billion for our schools," Shorten told supporters last month during a campaign rally in the electoral district of Longman, north of Brisbane.
Turnbull, who has struggled to implement his agenda because of the government's lack of a majority in the Senate, scored a major win in June by pushing through the largest income tax cuts in Australian history.
That followed the government's earlier passage of tax relief for small and medium-size businesses. Plans to cut taxes for companies with more than AU$50 million in sales annually have stalled due to a lack of support from minor parties and independents.
Immigration has emerged as another major election issue, weeks after the government passed new foreign interference laws that have strained relations with China, Australia's main trading partner and a major source of immigrants.
Opinion polls have shown a steady rise in anti-immigration sentiment among Australians as cities grow more congested, house prices rise and reports of Chinese interference circulate in the media.
Campaigning in Tasmania last week, Home Affairs Minister Peter Dutton, who holds the migration portfolio, trumpeted "common sense" moves by the government that resulted in a large drop in permanent migration last year.
Shorten shot back that temporary immigration is still on the rise, depriving Australians of jobs.
Labor currently holds all but one of the five seats being contested, with two -- Longman and Braddon in Tasmania -- viewed as toss-ups.
A Sky/Reachtel poll in June showed the government ahead in both marginal seats, although Labor's internal polling has reportedly showed it recovering ground in recent weeks
"Normally, PMs and their parties fear swings against them in one-off by-elections," Orr said, "especially in seats they had held. This is because they either risk losing their majority or, more commonly, they fear a backlash from some of their usual supporters registering a protest vote. This can lead to a media narrative of a government doomed to a general election defeat, and even a leadership putsch from fearful backbenchers.
"But this tranche of by-elections is unusual. Not only is there no government seat involved, but there are five by-elections, mostly in Labor seats, including a couple of very marginal Labor seats," Orr said.