South Australians will head to the polls on Saturday to decide whether they want Labor to continue in power after 16 years in government.
Premier Jay Weatherill faces an uphill battle after an electoral redistribution since the last election turned some of Labor's seats into notional Liberal ones.
Opposition Leader Steven Marshall will also have to fight to take power.
The emergence of Nick Xenophon's SA Best as a strong third contender adds another complication to an already tight race.
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The former independent senator is running candidates in 37 electorates, with Liberal-held seats such as Hartley and Mawson, the most likely to fall to the new party.
Mr Xenophon has refused to declare who he will support in the case of a hung parliament, saying it would depend on a range of factors, including which party receives the most votes and who was prepared to support their policies.
SA Best could also win enough of the vote in certain electorates to ensure no clear winner emerges, and the seat to be determined by preferences.
About 300,000 declaration votes are expected, including absentee, pre-poll and postal votes. They account for about a quarter of all voters, and won’t begin to be counted until Monday, meaning South Australians could be in for a long wait to find out who forms government, and who will be their next premier.
