On Friday, Iranian voters will head to the polls to choose the successor to Mahmoud Ahmadinejad, the hard-line Holocaust denier who has served as president for the last eight years.

In 2009, around 40 million people in Iran cast a ballot, a vote that was followed by massive protests — known as the Green Movement — against Supreme Leader Ayatollah Ali Khamenei for allegedly rigging the vote to deny victory to reformist candidate Mir Hossein Mousavi.

Khamenei won that battle, dampening hopes that Iran could chart a more democratic course. Furthermore, considering that ultimate power rests with the Supreme Leader, it's easy to dismiss the upcoming election as a sham.

However, despite outward appearances, the winner will actually be in a position to have an impact on Iran's direction.

Why vote at all?
Khamenei is called the Supreme Leader for a reason. He directs foreign and domestic policy, serves as the commander-in-chief of the armed forces, and controls the country's intelligence operations.

Yet, traditionally, the president has exerted autonomy in a well-defined political space, mostly concerning cultural and economic issues. In 1997, the Iranian people elected dark horse Mohammad Khatami, who at the time was serving as director of the national library. What came next were eight years of relative reform.

"Now, barely anyone can publish a book," said Parvaneh Vahidmanesh, a program manager at Freedom House who left Iran a month before the 2009 election. "But in the Khatami period, there were many books published inside of Iran and translated from Western countries. A lot of changes happened when Khatami was in power."

The president also appoints many top officials. Khatami picked reformers; Ahmadinejad chose his former colleagues in the Revolutionary Guards, an elite unit of the military that wields enormous power.

The international community often looks at Iranian politics through the lens of big issues — first and foremost Iran's suspected nuclear weapons program — that the president doesn't control. A reformist candidate isn't going to suddenly declare the end of the theocracy. He does, however, institute policies that affect the day-to-day lives of ordinary Iranians.

"There aren't big changes, because the president doesn't have a lot of power like in the United States," Vahidmanesh said. "But small changes can also help people."

How fair are elections in Iran?
Not very. The 12-member Guardian Council, six of whom are picked by the ayatollah, has the final say on which candidates can run. This year, it whittled more than 680 possible candidates down to eight. Two of them withdrew, leaving Iranians with six men to choose from. They include conservative frontrunner Saeed Jalili — Iran's top nuclear negotiator — and default reformist candidate Hasan Rowhani.

Iyad El-Baghdadi, a self-proclaimed "Islamic libertarian," summed up the absurdity of the system on Twitter:

As 2009 showed, even this limited form of democracy can be corrupted. Supporters of Mousavi cried foul when officials declared a winner only two hours after the polls closed.

The resulting Green Movement apparently spooked the Supreme Leader. This year, many foreign journalists who were granted press credentials in 2009 have been denied access by the Iranian government. Before, where there were colorful campaign leaflets and posters, there are only "plainclothes police officers hang around at major crossings, making sure there are no spontaneous gatherings," reports The New York Times.

The debate among reformists is whether to protest by not voting or to support a moderate candidate (relatively speaking) like Rowhani. Either way, it's unlikely to spark Arab Spring-style protests.

"We probably won't have something like the Green Movement like in 2009," said Vahidmanesh. "Because the reformist candidate, he doesn't have a lot of fans. Mossavi had a lot of followers; the people loved him."

What do Iranian voters care about?
In the words of James Carville: "It's the economy, stupid."

Iran is in the middle of an economic meltdown. Its currency, the rial, has lost two-thirds of its value over the last two years. Inflation is at its highest level in 18 years. In 2012, Western sanctions cut the country's oil revenues in half. It's no wonder that a recent poll put the economy on top of voters' list of concerns.

"It's the number one factor voters care about, followed by democracy and other issues," Vahidmanesh said.

Jalili, the Supreme Leader's reported favorite, has said he supports a policy of hard-line "resistance" against the United States and the pursuit of nuclear energy as fixes for the country's economic problems. Rowhani, on the other hand, has pledged "constructive interaction with the world," which includes trying to ease the sanctions.

Yes, Khamenei has the final word on policy, and has become even more authoritarian in the face of popular discontent — what Peter Jones at The Globe and Mail has called a "slow-motion power grab." But the very fact that Khamenei prefers one candidate over the other shows that something will be at stake when Iranians head to the polls.