Khamenei needs a high turnout "so that to the outside world he can say that his regime still has enough support to attract a majority of people to the polling stations," says Muhammad Sahimi, a professor at the University of Southern California and an analyst for the Tehran Bureau website.
The task is not easy for a regime that millions of Iranians believe stole their votes in 2009 for the surging opposition candidate Mir Hossein Mousavi. Hard-liners won that battle of wills, but many Iranians have now stepped away from politics as a result – making this de facto referendum on Khamenei's rule all the more significant for the regime.
"There is no energy in the air about this election at all," says a Tehran resident who could not be named. "The turnout numbers are predetermined, and no matter how many show up, they will declare 65 percent."
But the primary purpose of the vote, says this resident, is that Khamenei is "going to uproot [President Mahmoud Ahmadinejad's] dynasty, which he helped create."
In the 2009 elections, Khamenei endorsed Mr. Ahmadinejad's reelection as a "divine assessment." But since then Iran's political space has shifted to the far right, marked by vicious political infighting among conservatives and a power struggle between the supreme leader and Iran's divisive president.
A host of conservative factions are fielding candidates, but a number of those linked to Ahmadinejad have sought to hide their loyalty to the controversial president. Uneasy conservative opponents have charged his closest advisers with sorcery and leading a "deviant current."