In an interview with the Observer before she voted at the Whitfield All Age School early today, Simpson Miller said that the Jamaican people had made up their minds that a political change was necessary.
"I have urged all my candidates to be vigilant and tight on the ground as we are taking nothing for granted," Simpson Miller said.
"There is nothing to stop us tonight. I am a strong woman but I look to the Almighty for greater strength," she said.
Boosted by recent favourable showing in the polls, Simpson Miller said that the results were positive but the party still needed to bring the voters out.
"When Don Anderson gives a poll finding I have every confidence in that poll.
"Don Anderson is the don of all pollsters. He is the best since Carl Stone and I hope that what his poll has shown will in fact turn out to be accurate," she said.
Simpson Miller was due to vote around noon.