Australians will elect a new government on May 18, with early opinion polls pointing to a narrow victory by Bill Shorten’s opposition Labor Party.

Outgoing Prime Minister Scott Morrison confirmed the election date on Thursday, triggering five weeks of campaigning that will pit the incumbent Liberal-Nationals conservative coalition against left-centrist Labor. The Coalition has held power since 2013, but with dwindling majorities.

Public opinion polls suggest a Labor victory, but also show indecision by voters: a Newspoll on April 8 gave Labor 52% of the vote and the Coalition 48%, while an Ipsos poll on the same day had Labor ahead 53% to 47%.

Morrison said the election would be fought on economic issues, pointing to the fact his government had achieved the first budget surplus in years.

“You will have the choice between a government that is delivering a strong economy and will continue to do so, or Bill Shorten’s Labor Party whose policies would weaken our economy,” he said. “Keeping our economy strong is how we secure your future, and your family’s future.”

Australia’s opposition Labor leader Bill Shorten, right, and his deputy Tanya Plibersek face the media in Melbourne on April 11, 2019. Photo: William West / AFP

Shorten says it will be all about rising living costs and weak wages growth, two sore points with voters that Labor has successfully exploited. Labor will also do better on healthcare and hospital services, another issue that is getting media attention, as well as growing climate change concerns.

Labor almost pulled off a shock win in the 2016 poll with a scare campaign over Coalition plans to weaken Medicare, the country’s national health scheme, and has been quicker to support a public backlash against the heavy reliance on polluting fossil fuels, especially for power generation.

In contrast, Morrison is struggling to even set an effective agenda in an unwieldy alliance that includes far-right legislators backing privatization of Medicare and rural lobbies that want more government support for coal.

He will be mindful that his predecessor, Malcolm Turnbull, was dumped in an internal revolt in August after pushing an energy package that would have included more renewables. “Green” voters hit back by electing an independent in Turnbull’s old seat — a Liberals’ stronghold for decades.

A handful of other Liberals, including another former leader, Tony Abbott, could face electoral wipeouts over their role in Turnbull’s demise and their pro-coal stands. Abbott has an 11.1% edge in his Sydney seat, but polls suggest he could lose to an independent with a climate change platform.

“Climate change is a top issue in this election,” said Kelly O’Shanassy, chief executive officer of the Australian Conservation Foundation. “The community knows it. The parties know it. And the polls show it.”

Those polls indicate the issue is important to one-third of overall voters, rising to almost 50% in some urban seats. Rural voters are less concerned about coal being burned, but want action on water supply problems in major inland waterways that have partly resulted from climate change.

The ballot will be for 151 legislators in the House of Representatives and 40 in the Senate upper house — senators have six-year terms, against three years for lower house MPs. At least 76 seats will be needed to get a majority in the lower house and control the key position of Speaker.

Labor will require seven more seats, from a swing of 1%, to take power in the lower house, which sets laws. It currently has 69 seats, compared with 74 for the Coalition, with others held by small factions and independents.

However, the picture is clouded by recent changes in electoral boundaries and the addition of one seat that technically mean the Coalition enters the poll with 73 seats and Labor 72. Some previously safe seats will now become marginal, altering the balance of power and aiding independents.

“It creates the unusual situation where both the Coalition and Labor need to gain seats if they want to form government,” said Antony Green, a poll analyst with the Australian Broadcasting Corporation. The Coalition relied on small factions in its last government and the same scenario is possible.

Morrison’s party will start as underdogs, but his own popularity is on the rise. A Galaxy poll found that he was favored as national leader by 34% of voters, against 30% for Shorten. Yet neither came out of the poll especially well: Shorten was labeled “untrustworthy” and Morrison “smug and arrogant”, leaving both parties with work to do on their images before the election.