Updated

More than 16 million Australians are eligible to vote at elections on Saturday that are likely to deliver Australia's eighth prime minister in 12 years.

Opinion polls suggest conservative Prime Minister Scott Morrison will have one of the shortest tenures of the 29 men and one woman who have served in the post since 1901. He was only installed in August by government colleagues who had lost confidence in his predecessor Malcolm Turnbull.

His rival Bill Shorten is one of the longest serving opposition leaders in Australian history, having led the center-left Labor Party since it was last voted out of office in 2013.

Some election facts and figures:

___

COMPULSORY VOTING

Australia is one of a few countries that have made voting compulsory, so voter turnout is always high regardless of the level of interest in a campaign. The 91% of eligible voters who cast ballots at the last election in 2016 was the lowest turnout rate since failing to vote became illegal in 1924. Turnout at the previous election in 2013 was 93.2%. Failure to vote without an acceptable excuse attracts a 20 Australian dollar ($14) fine.

___

FAST VOTING

Electoral authorities strive to make voting quick and simple without the long queues that are characteristic of election day in many countries. The Australian Electoral Commission says 75% of voters at 7,000 polling booths around the country will have voted within 15 minutes of arrival.

___

PARTIES

The ruling conservative Liberal Party was founded in 1944 while its opponent, the center-left Labor Party, is Australia's oldest. Labor was formed by striking sheep shearers meeting under an Outback tree in 1891.

In 65 years of competing at elections, Liberal-led coalitions have been more successful than Labor. The conservatives have ruled for 47 of those years and have been led by the longest and second-longest serving prime ministers in Australian history.

___

ISSUES

Opinion polls show climate change has become a major concern for Australian voters. Labor has pledged to reduce Australia's greenhouse gas emissions by 45% below 2005 levels by 2030 and achieve zero emissions by 2050. The coalition government has committed to reduce emissions by 26% to 28% by 2030 and warns that Labor's more ambitious target would wreck the economy.

Tax, refugees and Australia's relationship with China are also issues.

___

RETURN TO STABLE LEADERSHIP

Both parties promise that whoever is elected prime minister will lead the country until voters next choose, probably in three years.

In the conservatives' six years in office, Liberal lawmakers have dumped two prime ministers and now have a third who has never faced an election as party leader.

Labor had a similar record during its previous six years in office. Labor ousted its elected prime minister for his deputy, then fired her to bring him back.

Both parties have changed their rules to make dumping a prime minister between elections more difficult.