CANBERRA, May 21 (ABC News) - Polling stations opened across Australia on Saturday for voters to decide whether Prime Minister Scott Morrison’s conservative government will defy odds and rule for a fourth three-year term.

Opposition leader Anthony Albanese’s center-left Labor Party is a favorite to win its first election since 2007.

But Morrison defied the opinion polls in 2019 by leading his coalition to a narrow victory.

Polls opened at 08:00 local time in eastern Australia on Saturday (23:00 on Friday GMT).

Voting is compulsory in Australia, and about 17 million people are expected to cast a ballot this time round.

They'll elect MPs for all the seats in the House of Representatives, and just over half the seats in the Senate.

The main political contenders are the ruling Liberal-National coalition and Labor. Either party will need to win at least 76 of the 151 seats in the House of Representatives - where the prime minister sits - to form a majority government.

If they cannot do that, they must try to win support from independent MPs, or those from minor parties.