Iranian reformists led by former president Mohammad Khatami endorsed the lone moderate contesting Friday's presidential election, seeking to mount a credible bid for the presidency after eight years of conservative control.
Khatami threw his weight behind Shi'ite cleric Hassan Rohani on Tuesday after Mohamad Reza Aref, the sole reformist candidate approved by Iran's Guardian Council but seen as lacklustre with scant public following, withdrew on Monday night.
The reformists' backing of Rohani, a former chief nuclear negotiator known for his centrist and conciliatory approach, is a clear effort to attract the votes of those Iranians hoping for greater freedoms and an end to Iran's diplomatic isolation.
Aref cited a request from Khatami in leaving a field of candidates dominated by conservative hardliners close to clerical Supreme Leader Ayatollah Ali Khamenei, who strongly influences the vetting decisions of the Guardian Council.
"With the heavy responsibility I have for the country and the fate of the people, I will give my vote to my dear brother Doctor Rohani," Khatami said in a statement on his website.
There are now six men on the presidential slate, mostly Khamenei loyalists separated by only shades of difference on major policy issues such as Iran's stand-off with the West over its disputed nuclear programme.
Most key Iranian policies that concern the world, such as its enrichment of uranium for nuclear fuel and its support for Syrian President Bashar al-Assad in his war with rebels trying to overthrow him, are decided by Khamenei.
But the Iranian president does exert indirect influence on broader policy, generally runs domestic affairs especially the economy of the oil-producing giant and is the highest-ranking public face of the Islamic Republic.
Khamenei, the most powerful person in Iran, has not publicly endorsed any candidate and insists he has only one vote in the election.
Khatami had first supported Akbar Hashemi Rafsanjani, but the pragmatic former president's candidacy was rejected by the Guardian Council last month, a move widely interpreted as meant to prevent a powerful challenger to Khamenei from taking office.
Friday's presidential vote will be Iran's first since 2009, when two reformist candidates called Mahmoud Ahmadinejad's re-election fraudulent, unleashing months of popular protests that were eventually crushed by security forces.
Mirhossein Mousavi and Mehdi Karoubi have been held under house arrest for more than two years, and reformists have been largely sidelined from power, with conservatives dominating Iran's parliament, presidency, and other major state bodies.
In that time, Iran has been hit with ever harsher sanctions imposed over its refusal to rein in nuclear activity and open it to unfettered U.N. inspections. The tightening sanctions noose has slashed Iran's oil exports and devalued its rial currency.
Iran's economic struggles, including inflation officially pegged at more than 30%, are likely to be the central issue for voters when they head to the polls on Friday.