The State Department says she will also meet election candidates in Haiti. The visit comes amid a political crisis in which Preval's preferred candidate to succeed him and a well-connected contender are deadlocked for a spot in a runoff.
The president's party has called on its candidate, Jude Celestin, to bow out because of pressure from the United States.
The United States says its continued support depends on following a recalculation of the election results by the Organization of American States, based on an analysis of fraud.
Celestin has yet to say if he will withdraw.
