The campaign has failed to excite many Iranian voters
Iranians go to the polls on Friday to elect a new president amid renewed fears of a showdown with the United States. Observers will be watching for the new president's views on the US "War on Terror" and the Middle East conflict, as well as for hints as to the fate of the reform process.
Ordinary Iranians appear unimpressed, however, and there are worries that turnout might fall below 50% for the first time since the Islamic Revolution in 1979.
While low turnout favours the conservatives - it is disillusioned reformists who are more likely to stay away - voter apathy is a worry for any future government.
The president is elected for four years and can serve up to two consecutive terms. His job is to ensure the constitution is observed.
After gaining approval from parliament, he appoints the Council of Ministers and oversees its work. He decides which government policies are put to parliament.
But the presidency is not Iran's top post. The supreme leader, Ayatollah Ali Khamenei, has more power.
He is the commander-in-chief of the armed forces and has the final say in political matters.
Reformers vs conservatives
The seven remaining candidates reflect Iran's political divide.
Former President Akbar Hashemi-Rafsanjani is considered a pragmatist, who could attract votes from both sides of the spectrum.
Former broadcasting chief Ali Larijani, former police chief Mohammad Baqer Qalibaf and Tehran Mayor Mahmud Ahmadinezhad are seen as conservatives.
Former Education Minister Mostafa Moin, former Majlis Speaker Mehdi Karrubi and current Vice-President for Sports Mohsen Mehralizadeh are reformists.
Only candidates approved by a supervisory body known as the Guardian Council are allowed to stand.
This time over 1,000 hopefuls including 93 women registered, but the Guardian Council ruled that only six - all men - qualified.
Another two - Mr Mehralizadeh and Mr Moin - were eventually allowed to stand after intervention by the supreme leader.
A candidate must win over 50% of the vote to win in the first round, otherwise there will be a run-off between the top two candidates on 24 June.
10-14 May: Candidates register
15-24 May: Vetting period
27 May-15 June: Campaign
17 June: First round
24 June: Possible Run-off
Analysts believe Mr Rafsanjani is in the lead, though he may not win enough votes to win outright.
The main reformist candidate, Mostafa Moin, might be expected to do well if turnout is high.
Citizens aged 15 and over are eligible to vote.
Mass parties have yet to become an institution in Iran. Political parties are often described as "associations of like-minded people".
Candidates in Iranian elections do not generally stand as party representatives. But they do try to win the endorsement of as many groups as possible.
Mr Rafsanjani has the support of political parties run by former officials during his presidency (1989-97), such as the Executives of Construction Party.
Mr Moin is backed by the main reformist party, the Islamic Iran Participation Front.
Mr Larijani in turn has the backing of traditional conservative groups, such as the Islamic Coalition Party and the Bazaar Association.
The Freedom Movement of Iran is the closest thing to an opposition party.
Its former leader, Mehdi Bazargan, was the Islamic Republic's first prime minister. But the movement fell out of favour and is barely tolerated today. Its current leader, Ebrahim Yazdi, was disqualified from standing in these elections.
The movement's demands include the release of all political prisoners, the lifting of the ban on many newspapers and the resignation of the Guardian Council.
The Guardian Council says it can ensure fair elections itself and so there is no need for foreign observers.
Indeed it is the total control exercised by this unelected body over the entire process that prompts human rights organisations to say the poll will be neither free nor fair.
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