Port-Au-Prince.– Latest interim results in Haiti's elections suggest the presidential race will go to a second, run-off round.
Former President Rene Preval, a one-time ally of ousted leader Jean-Bertrand Aristide, is now polling 50.2% with half the votes counted.
Mr Preval needs at least 50% to avoid a run-off. His supporters are alleging fraud after seeing his share drop from more than 60% in first results issued.
But international observers say the poll was free and fair.
Another ex-leader, Leslie Manigat, has 11.4%, while industrialist Charles Henry Baker has 8.3%, latest results show.
The country – the poorest in the Americas – is choosing a 129-member parliament as well as a new president.
The election process has so far been peaceful but the news of a possible second round could bring fresh instability, says the BBC's Claire Marshall in the capital, Port-au-Prince.
"We all voted for Preval. I really hope there isn't a second round because it will mean the election results were fiddled with and there will be trouble," one woman in an impoverished slum, where Preval enjoys strong support, told the BBC.
Charles Henry Baker has also alleged fraud, claiming some people were allowed to vote more than once because voter lists were not followed.
International observers say there were some minor procedural irregularities during Tuesday's voting but have deemed the election free and fair.
The US State Department has also declared the voting process free from fraud.
"The key here is that there is a high turnout. The Haitian people invested in this election process," state department spokesman Sean McCormack said.
However, in an implicit warning to Mr Preval – who once had strong links with Mr Aristide – the spokesman said the US expects the deposed leader to remain in exile in South Africa.
Mr Preval has told the BBC Mr Aristide may return if he wishes, although he would not tolerate the violent groups that have pledged allegiance to him.
In one positive sign, a prominent gang leader declared that his group would lay down their guns if Mr Preval – seen as the champion of the poor – becomes president.