Liberal leader Isobel Redmond says there is a mood for change which could result in her being South Australia's first woman premier.
Ms Redmond's Liberals are seeking to topple the Rann Labor government in today's election, which polls show is too close to call.
Ms Redmond, leader of the Liberals for only eight months, said she was "hopeful" but not confident of winning the election.
A Newspoll published in The Australian newspaper on Saturday showed support for the Liberals at 52 per cent, compared with 48 per cent for Labor.
"I am never ever confident coming into any election," Ms Redmond said after casting her vote in her Adelaide Hills electorate on Saturday morning.
"But certainly it (the Newspoll) is encouraging, it seems to me to indicate a mood for change in the electorate."
The Liberals' surge in political fortunes is remarkable given Ms Redmond is their fourth leader in four years.
Premier Mike Rann's campaign has been dogged by controversy, not least the claims of a former parliament house waitress Michelle Chantelois that she had a sexual affair with the premier.
The premier has denied the allegations and did not acknowledge the Chantelois factor when appearing at a polling booth in Adelaide's inner east on Saturday morning.
Mr Rann arrived at the Norwood polling station arm in arm with his wife Sasha and said he had no regrets about Labor's campaign for a third consecutive term in power.
"We know it's going to be a tight finish, all the polls have shown that," he said.
Both leaders said a result may not be known Saturday night due to the expected closeness of votes.
Labor holds a 10-seat buffer but a backlash is expected.
If Labor loses five seats, they also lose their majority government status.
Ms Redmond also refused to be drawn on the Chantelois controversy.
"It's something I have stayed away from for the whole campaign and it's something I will continue to stay away from," she said.
The Liberal leader said she was satisfied with her campaign.
"We have been able to not only put out positive policies of our own and make a very clear distinction between us and the other side, but also I think we have exposed some of the problems we have under a Labor government," she said.
Labor has consistently attacked Ms Redmond as not being ready to be premier, a claim she dismissed.
"The day after I became leader, I did wake up and think - I won't use the expletive - but I did wake up and think `oh my goodness, what have I done'," she said.
"But I'm confident that is just new job nerves.
"I am absolutely confident that if I wake up as premier of this state tomorrow, I will be ready to grab the job with both hands and run with it, just like I have grabbed the job of being leader of the opposition."
Polling booths close at 6pm (CDT).
