Iranians are voting Friday in the country's first elections since the Islamic Republic sealed a landmark deal with the United States and other world powers over its disputed nuclear program last year. It is also the first nationwide vote since moderate President Hassan Rouhani was elected in 2013 by promising to boost the economy, improve ties with the outside world and ease social restrictions at home.

Here is a look at some of the main issues surrounding the vote.

ELECTIONS IN IRAN?

The Iranian Revolution of 1979 that toppled the U.S.-backed shah led to the creation of what is known as the Islamic Republic of Iran. As the name suggests, the government has both theocratic and democratic elements.

The official with the most power in Iran is a senior Shiite cleric known as the supreme leader. Ayatollah Ali Khamenei currently holds that post — only the second person to do so — and his position will not be directly affected by Friday's vote. Iran's president and members of parliament are directly elected, as are members of an assembly that selects the supreme leader.

Not everyone who wants to run for office can, however. All candidates must be vetted and approved by the unelected Guardian Council, a constitutional watchdog dominated by hard-liners and made up of clerics chosen by the supreme leader and Islamic jurists.

WHAT ARE IRANIANS VOTING FOR?

Voters are casting ballots for representatives in two separate government bodies. One is the parliament, known as the Islamic Consultative Assembly. The other is the Assembly of Experts, a clerical body tasked with choosing the country's next supreme leader following the death of a current one.

The 290-seat parliament has limited legislative powers, and the bills it drafts are subject to review by the Guardian Council. The parliament has some oversight over the budget and public spending, and a say in the approval and questioning of government ministers.

The current parliament is dominated by conservatives who are wary of Rouhani's outreach to the West and his calls for less restrictive policies at home.

Gains for Rouhani's supporters in this balloting — even if they fail to win a majority in parliament — could limit hard-liners' influence over the house and increase the likelihood that the president could deliver on some of his legislative priorities. The outcome of the vote will also point to levels of support for Iran's various political factions ahead of next year's presidential election, when Rouhani is expected to seek a second term.

WHY DOES THE ASSEMBLY OF EXPERTS MATTER?

The 88-seat Assembly of Experts is officially charged with selecting the replacement for the supreme leader from among its members. The assembly is elected every eight years and there is a reasonable chance it could be called upon to select a successor during its next term.

Ayatollah Khamenei, who has the final say on all matters of state, is 76 years old. He underwent prostate surgery in 2014, renewing speculation about his health.

Former president Akbar Hashemi Rafsanjani, an assembly member, broke a taboo on speaking about the supreme leader's successor in December when he said that a committee within the assembly has begun putting together a list of possible successors to Khamenei.

Assembly members must be senior clerics and like parliamentary candidates, they must be approved by the Guardian Council.

WHAT ARE THE MAIN BLOCS?

Iran has dozens of political groupings and organizations, but no major, longstanding parties like in the West. Broadly speaking, the election is a showdown between hard-liners in one camp, and relative moderates supporting Rouhani and reformists on the other. There are also independent conservatives not aligned with either bloc.

Candidates across the board are putting an emphasis on improving the economy, which is hampered by a slump in oil prices, inflation and high unemployment. Rouhani's success in getting crippling international sanctions related to Iran's nuclear program lifted after years of negotiations is likely to boost moderate candidates.

But those seeking further reform face an uphill battle. Many reformist candidates were blocked from participating in the elections, and two opposition leaders who ran for president in the disputed 2009 election remain under house arrest. Other reformist activists are behind bars.

Candidates of various stripes also face a challenge in standing out from the pack in some constituencies. More than 1,000 candidates are competing for just 30 seats in Tehran alone.

WHO GETS TO RUN?

Only about 6,200 candidates out of the more than 12,000 who had sought to run were allowed to do so. The Guardian Council disqualified many for being seen as insufficiently loyal to the ruling system.

Candidates across Iran's political spectrum were disqualified, but reformists were hit particularly hard. Initially, only 30 of the 3,000 would-be reformist candidates for parliament were approved, according to nine reformist parties.

Later, the council reversed the disqualifications of around 1,500, including some reformists. In the end, around 200 reformists have been allowed into the race.

Among those disqualified from running for the Assembly of Experts was Hassan Khomeini, a grandson of the Islamic Republic's founder, Ayatollah Ruhollah Khomeini.

Observers see the bans as a way for hard-liners to limit the power of more reform-minded candidates as Rouhani looks to cash in on the optimism and promise of a stronger economy now that nuclear sanctions have been lifted.

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