TEHRAN — Iran’s presidential elections are perhaps among the most unpredictable worldwide. Except for the 2001 landslide re-election of Reformist President Mohammad Khatami, predicting the winner of the past five presidential polls has truly been a challenge. The May 19 vote is shaping up to be the most unpredictable yet.

In a new development this election cycle, the Principlist movement formed the Popular Front of Islamic Revolution Forces, popularly known by its Persian acronym, JAMNA, and adopted a candidate selection mechanism akin to the primaries held by Western political parties. The coalition, which includes top conservative figures, hopes to forge agreement on a consensus candidate to run against incumbent President Hassan Rouhani.

In balloting on April 6, JAMNA selected five men as prospective presidential nominees. A unity candidate will later be selected from among the five. All other potential Principlist contenders withdrew their candidacies after the primary.

Among those who stepped aside were Ezzatollah Zarghami, former head of Iran’s state broadcaster. He came in eighth place in the JAMNA primary but had announced his intention to run for the presidency March 15. Also stepping aside were former Islamic Revolutionary Guard Corps commander Mohsen Rezaei, who came in 10th place, and former nuclear negotiator Saeed Jalili, who had from the beginning rejected the very idea of JAMNA. Jalili announced his withdrawal through a statement shortly after the April 15 deadline for candidate registration had passed, and chose not to declare his support for any Principlist candidate.