But Bio and his supporters maintain the president has failed to deliver and does not deserve a second term.
"This is not a classroom when you are allowed to repeat after you have failed," he told reporters. "Today the economy of the country is in bad shape. The plight of our youths is very serious and it is not only a developmental issue but a security threat."
While Sierra Leone's economic growth has been good, analyst Tom Cargill says "youth unemployment and corruption remain dangerously high."
"The real issues facing Sierra Leone, particularly around youth unemployment, simply don't really appear to be being discussed in the way they should be if Sierra Leone is to escape its legacy of conflict," said Cargill, assistant head of the Africa program at the Royal Institute of International Affairs in London.
Observers say the upcoming election will mark a critical test.
"Peaceful elections resulting in a credible outcome are critical for consolidating Sierra Leone's hard-won peace and for demonstrating that the tremendous progress the country has made since the end of the hostilities one decade ago is irreversible," said United Nations spokesman Martin Nesirky.
The run up to Saturday's vote has been mostly peaceful, though the two main candidates squared off last month when Bio was accused of obstructing the president's convoy.
The main opposition party's final political rally went ahead peacefully Thursday, with large boisterous crowds dressed in the party's color of green flocking to the streets of Freetown. Many carried palm leaves, the symbol of the Sierra Leone Peoples Party. On Friday morning, others marched through the capital as part of a peace march aimed at ensuring a successful vote.
Koroma is expected to draw strong support in the north and in the capital, though he also appears to be making some inroads in traditional opposition strongholds.
Near the provincial capital of Bo, Augustine Pujah, 23, sported a red T-shirt emblazoned with the president's image. The young man dreams of studying science at a university and leaving his small community of Bevehun. For the time being, though, he and his friends make small change alongside the highway by selling palm wine in a yellow plastic jug.
"It's all about development," he says. "The president who comes to our aid is our leader."
Associated Press writer Clarence Roy-Macaulay contributed to this report.
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