Media reports from Haiti say international monitors will recommend that the country's government-backed presidential candidate be eliminated from a runoff election.
Demonstrators in Port au Prince demanded the resignation of the election commission after news reports about a leaked document from the Organization of American States.
According to the reports, the document said the OAS experts found that correct election procedures were not followed and that there were signs that vote tally sheets had been altered.
Preliminary results from the first round put former Haitian first lady Mirlande Manigat and ruling party candidate Jude Celestin in a runoff. Nearly 20 candidates contested the original elections.
Video clip: Demonstrators in Port au Prince