Iranians are preparing to go to the polls Friday in a parliamentary election boycotted by the reformist opposition, reducing the vote to a contest between conservatives who support or oppose President Mahmoud Ahmadinejad.

Iranian Supreme Leader Ayatollah Ali Khamenei has appealed for a big turnout that he says would represent an act of defiance toward Iran's enemies – a reference to Western powers leading a sanctions campaign against the Iranian economy. Western powers have been tightening sanctions to pressure Iran into stopping nuclear activities they fear are aimed at producing weapons. Iran says its nuclear program is peaceful.

Few Iranian reformists are among the 3,400 candidates vying for seats in the 290-member parliament. Iran's conservative government and clerical leaders have pursued a relentless crackdown on the reformist movement since it staged mass protests against Mr. Ahmadinejad's re-election in 2009. Reformists accused the Ahmadinejad government of rigging that presidential vote, a charge officials denied.

Iranian reformist leaders have been jailed, kept under house arrest or otherwise excluded by clerics from competing in the parliamentary vote. They have called on Iranians to boycott it.