Iranian President Hassan Rouhani, a moderate cleric (by Iranian standards), is seeking a second term as he faces off against a range of hardline conservative candidates.
The other remaining candidates are Vice-President Eshagh Jahangiri, who supports Rouhani and is thought to have simply entered the contest to shield him from attacks, fellow reformer Mostafa Hashemi-Taba, a former industry minister, and Mostafa Mirsalim, a conservative and former culture minister.
The election is largely viewed as a referendum on the 2015 nuclear deal struck with world powers shepherded by Rouhani's administration. In exchange for the International Atomic Energy Agency having more control over Iran's nuclear programme, Iran would keep a presence in the region, there would be a guarantee of security of the regime, and the USA would lift sanctions against it. Unsurprisingly, during the presidential campaigns, Iran's anti-Rouhani camp has taken to populism to work its way into the hearts and minds of the Iranian electorate, dismissing Mr. Rouhani's technocratic administration, led by the US -educated Foreign Minister Mohammad Javad Zarif, as being pro-western and anti-revolutionary.
Rouhani has stabilised the Iranian economy and brought down inflation but unemployment is high and his opponents have questioned whether his administration has done enough to bring tangible economic benefits to the country.
This election marked Qalibaf's third presidential campaign, having previously lost running to the left of hard-line President Mahmoud Ahmadinejad in 2005 and to the right of Rouhani in 2013.
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"But there are issues that my legal government was not able to resolve", Rouhani said on Monday, referring to his failure to end house arrests - in part due to his lack of authority over hardline security forces answerable only to Supreme Leader Ayatollah Ali Khamenei under Iran's complex system of dual theocratic and republican government.
Only minutes after the news, posters appeared on conservative media showing the black-turbaned Raisi alongside Qalibaf, wearing a yellow safety helmet.
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Some conservatives had been unhappy that Qalibaf was standing again and risking a split in the anti-Rouhani vote.
"I studied five years at one of Iran's top architecture universities but what I'm doing now could be done by someone who learnt the software on a two-month course", said 24-year-old designer Parnian Dalili, who nonetheless felt lucky to have landed a job at all.
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The Presidents' Trophy winners responded with a three-goal barrage over the final 20 minutes that extended their season. Oshie's goal came with Crosby watching from the penalty box, off for hooking the ever-irritating Tom Wilson.
Known as Astan Quds Razavi, it runs Iran's holiest shrine as well as a huge business conglomerate with interests in everything from IT and banking to construction and agriculture.
Khamenei, Iran's final arbiter on all matters of state, intervened last week as the campaigns became more confrontational, calling on candidates to avoid "immoral" outbursts that could damage the nation.
"Raisi may not have a very strong vote bloc, but as some polls have suggested, his negative vote is smaller than Qalibaf's", said Hossein Rassam, now an independent analyst.
Qalibaf's endorsement may push those so far unexcited by the election into voting for Rouhani, said Cliff Kupchan, the chairman of the Eurasia Group.
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