A high turnout may be especially important now, in light of Iran’s darkening economic prospects and increasingly fragmented political scene. New sanctions imposed this year by the United States and Europe have had unprecedented effects on Iran’s private sector and middle class. And Ayatollah Khamenei appears to be increasingly unpopular, with some conservatives breaking a taboo by criticizing him openly.

At the same time, most analysts say the government will report a turnout of 60 percent or higher, regardless of what happens on Friday. Unlike in 2009, protests are unlikely even if there are clear indications of fraud, because expectations are so low, said Mehrzad Boroujerdi, a professor of political science at Syracuse University. Nor is a high turnout a clear sign of support for the state: Many Iranians will vote to avoid getting into trouble, because their national ID cards are stamped at the polls.

If there is any drama in the election, it has to do with the bitter conflict between two groups of conservatives: allies of President Mahmoud Ahmadinejad, and a hard-line faction of clerics and Revolutionary Guards commanders claiming to back Ayatollah Khamenei. Although no one in Iran’s political class dares to challenge Ayatollah Khamenei openly, the president has successfully elevated the power of his office since he was first elected in 2005, and hopes to maintain his influence through allies in Parliament even after his second term ends in 2013. Those ambitions have bred tensions with Ayatollah Khamenei, who has final authority in Iran’s government, and the two men had an unusual public spat last May. Mr. Ahmadinejad and his allies, including his controversial chief of staff, Esfandiar Rahim Mashaei, have raised large amounts of money through the privatization of state industries since 2005, and some analysts say they could use that money to help elect their favored candidates, or even bring new Parliament members to their side after the election.

“Ahmadinejad wants to take control of the Parliament for two main reasons,” said Muhammad Sahimi, a professor at the University of Southern California who writes for the Web site Tehran Bureau. “He wants to prevent his rivals in Parliament from impeaching him — as they’ve been threatening for a long time — and he wants, through Parliament, to influence the presidential election of 2013.”