CANBERRA, March 17 (Xinhua) -- A record number of voters have enrolled to have their say in one of the closest election in South Australian history.

The Australian Electoral Commission (AEC) confirmed on Saturday that more than 1.2 million South Australians were eligible to vote in the election, an increase of approximately 60,000 over the last election.

There are three parties with a chance of forming government with former Federal Senator Nick Xenophon's centrist SA-BEST joining the incumbent center-left Australian Labor Party (ALP) and conservative Opposition Liberal Party in the race.

Despite SA-BEST's poll numbers falling off as the election campaign winded down, Xenophon could still hold the balance of power with a hung parliament, whereby no party manages to secure a governing majority, a live chance.

A Newspoll released on Friday night revealed that SA-BEST's primary vote had fallen four points from 21 percent to 17, trailing the Liberals on 34 percent and the ALP on 31 percent.

Regardless of the result, SA-BEST's campaign will be seen as a landmark moment in Australian political history with Xenophon managing to disrupt the country's two-party system for the first time.

The slight edge in primary vote is to be of little comfort to Liberal leader Steven Marshall who lost the 2014 election on preferences despite his party garnering 44.7 percent of primary votes compared to Labor's 35.8 percent.

If victorious, Premier Jay Weatherill's ALP will form government for a historic fifth consecutive term; taking it past the milestone of 20 consecutive years in power.

Energy prices have been the hot button issue of the campaign with Marshall criticizing the state's increasing dependence on renewable power under Weatherill's leadership, saying it was the main factor in soaring electricity prices.

Weatherill used the final day of the campaign on Friday to announce that British billionaire Sanjeev Gupta was going to build the world's largest lithium ion battery surpassing the Tesla facility also in SA.

"This is the single biggest issue facing South Australians," Weatherill said of the energy crisis.

"We can't turn back now. The momentum is growing."