Sunday's election may push parties to stake out harder positions in the October parliamentary elections against sharing power with ideological opponents.
Tunisia's presidential election on Sunday is the most unpredictable in its short experience of democracy, a contest with no overwhelming front-runner at a time of economic angst.
It will shape not only indebted Tunisia's approach to foreign relations and the vexed issue of public spending, but also test its consensus model of politics and the way it practices democracy.
While outsiders, especially in Arab states, are watching the fortunes of the Ennahda party, many Tunisians have been engrossed by the candidacy of a media magnate who was imprisoned last month on suspicion of tax fraud, and whose campaign has focused on the poor.
However, after years of rising unemployment, high inflation and reduced spending on public services and subsidies, many Tunisians feel frustration with politics, adding to uncertainty over the outcome and turnout.
"Things aren't clear. I still don't see a candidate that is qualified and worthy of running Tunisia," said Houda Ben Ayed, a woman waiting at a tram stop in Tunis.
Though Sunday's vote is unlikely to produce a clear winner, with the two top candidates to hold a run-off if none of them win an outright majority, it will still influence a parliamentary election on October 6.
Tunisia's revolution began with the self-immolation of a desperate vegetable seller in December 2010, then mass protests that forced former president Zine el Abidine Ben Ali to seek exile in Saudi Arabia and soon spread across the Arab world.
Eight years on, Sunday's highly competitive, wide open election shows how Tunisia's path to democracy has run smoother than in Egypt, Libya, Syria, Yemen or Bahrain, where people attempted to follow its example in throwing off autocratic rule.
The televised debates between most of the 24 men and two women running for office were widely watched by voters hoping to whittle down their choices - a far cry from the unopposed 99% election victories under Ben Ali, now lying sick in a Saudi hospital.
The crowded field boasts some of Tunisia's biggest names, including current and former prime ministers and the first ever presidential candidate from the country's strongest party, as well as the detained media magnate, Nabil Karoui.
No incumbent is running, since former President Beji Caid Essebsi died in July aged 92 and the interim president, Mohammed Ennaceur, did not stand.
Power sharing or polarisation
Most elections since the revolution have led to power-sharing agreements between the rival parties, as politicians sought to avert dangerous polarisation between ideological opponents or to present a united front to deal with economic crisis.
It is uncertain whether that consensus model will continue. Sunday's election may push parties to stake out harder positions in the October parliamentary elections against sharing power with ideological opponents.
The president, although the most significant figure in national politics, has direct control only over foreign and defence policy, with the prime minister chosen by parliament overseeing most other portfolios.
Several candidates have challenged this arrangement, calling for changes to the constitution to give the president more power. It is one way in which Sunday's vote will affect how Tunisian politics work.
Case of media magnate Karoui
The case of media magnate Karoui is another. His opponents say he has used his charity and his television station illegally, and that if he wins, it would represent a blow to democratic principles.
Karoui denies wrongdoing and complains his detention has denied him the right to contest the election on equal terms with his rivals.
On Friday a court said he would stay behind bars while waiting for a final verdict in the case.
His supporters say his arrest shortly before the start of the campaign over a tax fraud case that was initiated years ago is evidence of undemocratic behaviour on the part of the authorities, who they say are trying to silence him.
Continuity is most clearly represented in the race by Prime Minister Youssef Chahed, whose administration has implemented economic reforms since 2016 as part of an IMF loan programme.
Whatever his fate in Sunday's poll, those reforms highlight the difficulties that the next president and government will face, caught between popular demands to raise spending and the insistence of international lenders that Tunisia cut back.
A strong showing for the Ennahda party would not necessarily lead to a big shift in policy. Banned under Ben Ali as a religious party, it has played a big role in most governments since the revolution.
Though it has pushed a more moderate image in recent years, portraying itself as a "Muslim Democrat" party, many Tunisian liberals worry it still harbours a more conservative religious agenda.
The main focus of its extensive party machine - the most established in the country - has been on the parliamentary election rather than the presidential race, which it is entering for the first time with deputy leader Abdelfatteh Mourou as its candidate.
However, in a possible sign of its concern about the tightness of the race, party leader Rached Ghannouchi has called on other conservative candidates to withdraw.