Mohammad-Reza Aref, the sole reformist candidate in the June 14 Iranian presidential vote, has withdrawn from the race after receiving advice from reformist former president Mohammad Khatami, his website has reported.
"At dusk on Monday... I received a letter from Mohammad Khatami... he said it would not be wise for me to remain in the race," Aref wrote in his withdrawal statement on Tuesday.
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In recent days, calls have grown from within the reformist camp for Aref to quit in favour of the moderate candidate Hassan Rouhani.
Aref 's withdrawal from the race is the second in two days.
Ex-parliamentary speaker Gholam-Ali Haddad Adel, seen as close to Supreme Leader Ayatollah Ali Khamenei, pulled out of the race on Monday without endorsing any of the four remaining conservatives standing for election.
He was not considered a frontrunner in the presidential poll.
Khatami's advisory council in a statement threw their backing behind Rouhani as the "reformist camp candidate".
Rouhani was Iran's former top nuclear negotiator under Khatami.
He also served as top security official under the former president Akbar Hashemi Rafsanjani, whose support he still has.