Tehran's Prosecutor Ali Alghasi Mehr told presidential candidates on Sunday "not to cross the Islamic Republic's red lines," and said that violations "would be strictly dealt with." He instructed judges in Tehran to "firmly confront those who cross the red lines regardless of a candidate’s position."

The leading candidate, after the controversial elimination of two key hopefuls, is the Judiciary chief Ebrahim Raeesi (Raisi), who controls both prosecutors and courts. He has not resigned from his post to run for president and the threat about “red lines” can be taken as intimidation by a powerful outfit he controls.

Nearly all the candidates approved by the hardliner political establishment to run for the June 18 poll did not challenge the prosecutor’s threat, but not everyone remained silent. Reformist candidate Mohsen Mehralizadeh wrote in a tweet: "How do they dare threatening presidential candidates and defining red lines?!"

Mehralizadeh then charged, "If the Chief Justice is worried that criticizing him in this unfair competition would be treated as criticizing the Judiciary, he had better resign his post as Judiciary Chief or withdraw his candidacy for the Presidential election."

Whatever “red lines” exist, candidates seem not to have heeded an instruction from Supreme Leader Ali Khamenei not to make unrealistic promises. Deputy Parliamentary Speaker Amir Hossein Ghazizadeh Hashemi, a principlist member of parliament, has said that he would as allocate 5 billion rials ($20,000) to every newly married couple.

Speaking to a meeting with maddahs (religious eulogists) in Tehran at the weekend, Hossein Ashtari, Iran’s police chief, urged them to "bring everyone to the polls to vote." Ashtari also threatened to "deal with those who tell the public not to participate in elections." Some would-be candidates barred from the election, including both former president Mahmoud Ahmadinejad and the reformist Mostafa Tajzadeh, have said they will not now vote while stopping short of calling for a boycott. The reformist parties have said they will not support any candidate.

Ahmad Alamolhoda, Raeesi's father-in-law and the Friday prayer leader in Mashhad, in north-eastern Iran, also warned WHEN over anyone advocating an election boycott, saying it would amount to abandoning Islam.  Iran is one of 12 states worldwide where apostasy can in theory carry the death penalty.

In whittling down the number of candidates – this time from around 600 who registered to seven – the Guardian Council invariably faces criticism. But this time critics include Masih Mohajeri, editor of Jomhouri-e Eslami newspaper, who has suggested the selection has ensured who will win, meaning Raeesi.

Some on social media are equally certain, joking that that while the winner of the United States 2020 presidential elections was not known for a month, people in Iran know who will be their next president one month before voting.