PORT-AU-PRINCE, Haiti — Senate leader Jocelerme Privert took office as Haiti’s caretaker president with one real task: Three months on, yet another voting date has fallen by the wayside as political infighting continues to snarl election efforts. [...] his provisional administration got off to a sluggish start, and only recently appointed a commission to verify contested elections held last year that many Haitians believe were rigged to benefit Tet Kale, the party of previous President Michel Martelly. Laurent Dubois, a Haiti historian at Duke University, said election postponements and declarations of fraud have been a consistent part of the nation’s electoral process since the overthrow of dictator Jean-Claude Duvalier in 1986. In 2010, outgoing President Rene Preval was suspected of rigging the vote to elect his preferred successor, Jude Celestin, sparking violent clashes between Martelly’s supporters and U.N.