By Pascal Fletcher
PORT-AU-PRINCE (Reuters) - Haitian voters will choose on Sunday between a brash entertainer and a scholarly law professor for the unenviable job of trying to lead reconstruction of one of the world's poorest and most battered countries.
But even before it takes place, the presidential run-off vote is being overshadowed by the expected return from exile of former President Jean-Bertrand Aristide, whose 2004 ouster in an armed rebellion harks back to a turbulent past many Haitians would like to leave behind.
The election is being closely watched by the United States and other Western donors that have invested heavily in trying to steer the fragile Caribbean state to lasting stability, and bankrolling its recovery from a crippling 2010 earthquake.
Michel "Sweet Mickey" Martelly, a 50-year-old carnival music star with no government experience, goes up against 70-year-old opposition matriarch and law professor Mirlande Manigat in Sunday's vote.
Manigat won most votes in the first round of voting in November but Martelly, a popular and wealthy star of Haiti's Konpa carnival music, has surged and recent polls show him ahead.
"It's a big challenge for democracy in Haiti," said Gregory Brandt, president of the Franco-Haitian Chamber of Commerce and an adviser to Manigat. "It's the first time there is a second round, and the first time there is this contrast (in personalities)."
As if the risk of political instability was not already high enough in the Western Hemisphere's least developed and most volatile country, the expected return of charismatic leftist former Catholic priest Aristide has added another unpredictable ingredient to the mix.
The former leader, who still commands a fanatical following among the poor in Haiti, wants to return home from exile in South Africa before the election, his lawyer said on Thursday, although the exact timing of his intended homecoming is unclear.
"It's a wild card," said Ambassador Colin Granderson, who heads the Organization of American States/Caribbean Community observer mission to the elections.
The United States, which flew Aristide out of Haiti during the rebellion against him seven years ago in what he termed a "kidnapping", says he could destabilize the country if he returns before Sunday, and sees it as a move to influence the election.
Even without the complication of Aristide's return, Haiti's electoral officials and foreign aid partners desperately hope the election will not descend into the chaos, unrest and fraud allegations that marred the first round of voting on November 28.
The run-off campaign has generally been calm but Granderson is concerned by a "deterioration of the rhetoric" over the last week, which also saw reports of Manigat rallies being disrupted by stone-throwing supporters of her rival Martelly.
Electoral authorities have intensified a public information offensive to try to avoid the confusion in the first round, when many voters could not find where to cast their ballots.
Martelly shrugs off critics' claims that past outlandish stage antics like stripping in public and wearing wigs make him unsuitable for president, and he has drawn large crowds in an energized campaign which projects him as a straight-talking man of the people.
"This campaign is not about Mickey Martelly. It's a campaign to send all of Haiti's children to school for free," he told cheering supporters at one rally this week. His populist message taps into the impoverished population's huge unsatisfied needs in almost every aspect of daily life.
Manigat is a Sorbonne-educated constitutional expert, former senator and wife of former President Leslie Manigat, who was ousted in a coup shortly after his 1988 election.
She portrays Martelly as a dangerously inexperienced novice and has accused his fanatical young followers, who often wear or display the Martelly party color of pink, of attacking her campaign rallies, calling them a "pink militia".
She argues such militias inspired by a populist personality could be the first signs of a dictatorship in the making.
In contrast, Manigat says she has the background and the experience to be a conciliator of Haiti's fractious political forces and unite them around the goal of reconstruction.
"We need calm and serenity for these elections," she said, adding it would be preferable if Aristide came home after the vote because his presence could cause "agitation".
(Additional reporting by Donald Wislon, Editing by Kieran Murray)