|Foreign donors hope the poll will produce the stability needed to rebuild the quake-crippled nation [Reuters]
Voting has started slowly in Haiti's presidential runoff, with some polling stations unable to open on time.
In the capital Port-au-Prince, some stations opened several hours late on Sunday because materials such as ink to mark voters' fingers and labels to mark the urns had not arrived.
"In Croix-des-Bouquets [outside the capital], some poll workers arrived late, so the polling stations could only open 10 to 15 minutes later," said Colin Granderson, the deputy secretary general of the regional CARICOM bloc who is leading an international observer mission to the quake-shattered country.
But Edmond Mulet, head of the UN mission in Haiti, said there were fewer delays and other problems than in the November 28 first round, which was marred by disorganisation and allegations of fraud.
"Everything is peaceful, is more or less OK, much better than November 28,'' Mulet told The Associated Press
as he toured polling stations.
Blue-helmeted Brazilian UN troops guarded voting centres along with Haitian police, and UN armoured vehicles rumbled through the streets, many still strewn with debris left from last year's earthquake.
The election presents Haiti's 4.7 million voters with a choice between a political newcomer and singer Michel Martelly and former first lady Mirlande Manigat, a law professor and opposition matriarch.
Recent opinion polls have shown Martelly slightly ahead of Manigat.
The UN, which is supporting the election, says voting improvements have been made since the chaotic November vote to enable a clear, credible outcome for the runoff in one of the world's poorest states.
"I need a president to change the situation of the country," Adeline Hyppolite, a voter who cast her ballot in the Petionville district of the capital, said.
"We are hoping for a better life ... but only God knows. We hope we'll find the change we're looking for."
The Caribbean state needs a capable leadership and government to steer a post-quake reconstruction that requires billions of dollars of foreign assistance.
UN Secretary-General Ban Ki-moon and other international leaders appealed for a calm, transparent vote.
Weighing on many Haitians' minds as they cast their ballots is the reappearance of a political heavyweight from the past, former President Jean-Bertrand Aristide, who arrived back from exile on Friday.
The return of the left-wing populist and former Catholic priest who still commands a big following in Haiti was
opposed by the US and UN as potentially disruptive to the polls. But Aristide is not a candidate and aides have said he will stay out of politics.
Mixed in with banners welcoming Aristide, the duelling slogans of the rival candidates were plastered on walls.
Martelly's "Tet Kale" slogan, a Creole play on words that refers to his shaven head and also means "all the way" to convey his promise of forceful change, contrasts with Manigat's more homely "Banm Manman'm" (Give me Mummy) slogan that seeks to bolster her image of experience and responsibility.
Under Haiti's election law, the Provisional Electoral Council is due to announce preliminary results from the runoff on March 31, with final results being confirmed on April 16.