Tunisia stands out in a region roiled by violence, chaos and the resurgence of despotism. If there is a democratic handoff for the head of state, it will mark the most peaceful transition of power born from the wave of revolts that swept through the Middle East in 2011.

The race is close. And the choice is being cast as a vote between a soft version of the old regime, represented by Essebsi, and a disheveled populist, Marzouki, who draws power from an Islamist base.

A major reason that a peaceful transition is possible in Tunisia is that the Islamists didn't seek to dominate when they came to power.

"The best way to describe the Tunisian experience is the experience of consensus and not the experience of conflict," says Rachid al-Ghannouchi, a founder of Tunisia's most powerful Islamist movement, Ennahda.

He says his party wanted to avoid polarizing the populous like the Muslim Brotherhood did in Egypt. There, the brotherhood came to power in 2012 but were thrown out in a military coup a year later that included a violent crackdown against the group.

So Ghannouchi's party agreed to dissolve the Cabinet that it controlled. And to avoid conflict between secularists and Islamists, it didn't put forward a presidential candidate.

Ghannouchi says that in the long run, it's wise politics.

"For us, the success of the democratic experience is more important than our party's interests," he says. "Allowing the democratic experience to survive, even with a man from the old regime, will allow us the chance to come back to power in the future. But if the experience fails, then everything will fail and we will enter the world of terrorism and chaos."

That chaos is visible throughout the region. Next door in Libya, two rival governments and their militias are wreaking havoc. Syria is in a civil war and Yemen is on the brink of collapse.

"Tunisia is the standing tree in a collapsing forest from here to Iraq," says Ghannouchi.