Updated

The U.S. ambassador to the United Nations said Thursday that Haiti must accept the Organization of American States' call to replace the candidate backed by President Rene Preval in a disputed presidential election.

American Ambassador Susan Rice said that Haiti has to sponsor a credible election if it wants to retain the support of the United States and the international community.

The OAS, a regional political grouping in the Americas, has called for government construction official Jude Celestin — who is backed by Preval — to be dropped to third place in the preliminary tally because of widespread election fraud.

He would be replaced in second place by singer Michel Martelly, who would face a runoff election with former first lady Mirlande Manigat, the top vote-getter.

Haiti's electoral commission has said it will consider the OAS recommendation as one among many appeals filed before the Jan. 24 deadline, but will not be bound by it.

"Sustained support from the international community, including the United States, requires a credible process that represents the will of the Haitian people, as expressed by their votes," Rice told the U.N. Security Council.

Rice spoke during a council briefing on the situation in Haiti one year after a devastating earthquake killed more than 200,000 people.

U.N. peacekeeping chief Alain Le Roy warned that Haiti could face more political instability unless the government accepts the OAS electoral recommendations.

"Should the (electoral council) decide otherwise, Haiti may well be faced with a constitutional crisis, with the possibility of considerable unrest and insecurity," Le Roy told council.

The U.N. has a 12,000-strong peacekeeping operation in the Caribbean country.

Street riots erupted in December when provisional electoral results showed that Celestin had edged out Martelly, a popular figure known as "Sweet Micky," for second place and the chance to advance to the runoff. Martelly supporters barricaded streets and burned Celestin's campaign headquarters to demand their man be named president.

A Jan. 16 runoff was postponed and the OAS called in to review the allegations of fraud.

Haiti's political situation remains shaky one year after the earthquake. A cholera epidemic has complicated reconstruction efforts, and this week's surprise return of former dictator Jean-Claude "Baby Doc" Duvalier has provided a new distraction.

After the briefing, Le Roy acknowledged to reporters that "for the time being, the political situation is very complicated" with Duvalier's return.

It could become even more complicated because former President Jean-Bertrand Aristide is saying he might return as well.

"Given the continuing turmoil surrounding the November 2010 election, the United States is concerned about the unpredictable impact that Duvalier's return may have on Haiti's political situation," Rice told the council.

Duvalier was 19 when he assumed the presidency following the death of his father, Francois "Papa Doc" Duvalier, and ruled from 1971-1986.

The two leaders presided over a dark chapter in modern Haitian history with a secret police force known as the Tonton Macoute torturing and killing political opponents.

"My government is clear about Duvalier's notorious record of human rights abuses and corruption," Rice said. "The situation on the ground is obviously fluid, but the government of Haiti seems to be taking initial steps to hold Duvalier accountable for his actions during his time ruling Haiti."