Leaders of South Australia's three major political parties will deliver their final pitches to voters ahead of this weekend's election at a people's forum.
Premier Jay Weatherill, Opposition Leader Steven Marshall and SA-BEST Leader Nick Xenophon will take questions on Wednesday night from 100 undecided voters selected by polling firm Galaxy.
The voters will be asked to declare a winner at the end of the debate, which will be presented by The Advertiser and Sky News.
Mr Xenophon will be particularly keen to grab last-minute votes, after a poll released on Tuesday showed he is in danger of failing to win his own seat at the March 17 election.
In an Advertiser-Galaxy poll of 590 voters in the seat of Hartley, incumbent Liberal MP Vincent Tarzia leads the SA-BEST party leader 51 to 49 per cent in the two-party preferred vote.
Mr Tarzia also polled the highest primary vote at 38 per cent, ahead of Mr Xenophon on 30 per cent and Labor candidate and former minister Grace Portolesi on 22 per cent.
Mr Xenophon called the contest a "two-horse race" and appealed to voters to consider where their preferences will be directed.
"My message to Labor and Greens voters is that if they vote for Labor or the Greens in the seat of Hartley they'll effectively be delivering the seat to the Liberals and to Mr Marshall," he said.