Polls to take place on May 18 pitting Labor Party’s Shorten against Morrison, who took over as PM last August.

Australia‘s prime minister has called a May 18 election that will be fought on issues including climate change, asylum seekers and economic management.

While Scott Morrison’s conservative coalition is seeking a third three-year term, he is the third prime minister to lead a divided government in that time, having been in the post since last August.

“We live in the best country in the world but to secure your future, the road ahead depends on a strong economy. And that’s why there is so much at stake at this election,” Morrison told reporters on Thursday after advising the governor-general to authorise the election.

“You will have a choice between a government that is lowering taxes … or Bill Shorten’s Labor party that will impose higher taxes that will weigh down our economy.”

The election pits Shorten, a former labour union leader who has presented himself as the alternative prime minister for the past six years, against Morrison, a leader who the Australian public is still getting to know.

Opinion polls suggest centre-left opposition leader Shorten will become the eighth prime minister since the country plunged into an extraordinary period of political instability in 2007.

“The main liability for Morrison and his coalition is the political instability within his own party,” said Al Jazeera’s Andrew Thomas, reporting from Sydney.

He added that the reason behind having three prime ministers since 2013 was “because they have been seen to be consistently behind in the polls”.

Morrison is seen as the architect of Australia’s tough refugee policy that has all but stopped the people-smuggling traffic of boats from Southeast Asian ports since 2014.

The policy has been condemned by human rights groups as an abrogation of Australia’s responsibilities as a signatory to the United Nations Refugee Convention.

Climate change policy is a political battlefield in a country that is the world’s largest exporter of coal and liquefied natural gas and has been one of the world’s worst greenhouse gas emitters on a per capita basis because of its heavy reliance on coal-fired power generation.

Disagreement over energy policy has been a factor in the last six changes of prime minister.

“It’s an enormous mountain to climb,” said political science professor Paul Williams from Griffith University in Brisbane.

“If he [Morrison] were to pull this off it would be one of the greatest comebacks in political history.”