Clinton's visit to Haiti Sunday came as the U.S. government tried to get Preval to accept conclusions of Organization of American States election monitors that his chosen candidate, Jude Celestin, did not qualify for a runoff.
"We've made it very clear we support the OAS recommendations and we would like to see those acted on," Clinton told reporters.
Clinton met with Preval, Celestin and the candidates that the OAS determined were the top vote-getters in the Nov. 28 elections, former first lady Mirlande Manigat and singer Michel "Sweet Mickey" Martelly, CNN reported.
When it announced its preliminary results in December, the Haitian electoral commission said Celestin, not Martelly, qualified for a runoff, prompting widespread riots in which five people died. After the OAS report, the ruling party said Celestin would drop out of the race, which he hasn't done yet.
The electoral board is scheduled to release final results this week. The second round of the presidential election is scheduled for March 20. Preval's term was to end Feb. 7 but emergency legislation passed by Parliament allows him to remain in office several more months.
"There are many complications that are legitimate concerns raised by various figures in Haiti, not just President Preval, but others, about what is the best compromise," Clinton said. "[If] there are ideas that we should follow up on, we will take those into account. But we want to see the OAS recommendations followed."
The Obama administration recently increased pressure on Haiti by revoking U.S. visas of several Haitian government officials and citizens close to Preval.
Clinton visited a clinic where victims of a cholera epidemic are being treated. Since fall, more than 3,500 people have died of the disease while the impoverished island nation struggles to recover from a devastating earthquake a year ago.
"We may have passed the immediate emergency phase but now we're in the middle of a long-term reconstruction effort on behalf of the Haitian people," Clinton said after her arrival at the Toussaint Louverture International Airport.
"I am here today with a very simple message: The United States, our government and our people, will stand with the Haitian people. We want to see the reconstruction continued. We want to see the voices and votes of the Haitian people acknowledged and recognized. We want to see you move forward into a future that really meets the promise that has so often been held out as the potential of Haiti."