Ghalibaf and Raisi clashed with Rouhani during last Friday's nationally televised debate.
Summary⎙ Print At a campaign rally, President Hassan Rouhani said Iranian officials are ready to negotiate with the United States on non-nuclear issues.
Seemingly encouraged by the country's Supreme Leader, Ayatollah Ali Khamenei, hardliners have accused incumbent Hassan Rouhani of wanting to import Western decadence and to open up Iran to the destructive power of US business.
Qalibaf had been under pressure from fellow hard-liners to fall in behind Raisi. Some also have speculated that Qalibaf could serve as a vice president in Raisi's administration, in exchange for his support.
On Sunday, Rouhani touched down in the western Lorestan province before addressing thousand of supporters, many of them clad in purple, at the university in Khorramabad. If no candidate breaks that threshold, the two top-placed candidates will face off in a second round scheduled for a week after the first vote.
In announcing his decision, Qalibaf asked his supporters "to contribute their full capacity and support for the success of my brother, Ebrahim Raisi".
Raisi called Qalibaf's withdrawal "revolutionary", the conservative news agency Tasnim reported the cleric as saying on Monday. His landmark policy has been the reduction of sanctions against Iran via rolling back on the county's nuclear programme.
Raisi needs to reach out to a wider conservative base in the next few days, Bassiri Tabrizi said. "We can not take the renewal of his mandate for granted".
They were not happy that the maverick Tehran mayor was standing again and thereby raising the risk of splitting the anti-Rouhani vote. "We have resolved some problems and bigger problems remain for us to resolve on this hard path with him", Khatami said in a video message, "It is now your turn to renew your vote for our dear Rouhani in order to strengthen hope for a better future".
Qalibaf had been running for president for the third time after being defeated in the 2005 and 2013 votes.