A wave of arrests signals a conservative crackdown as Iran prepares for national elections scheduled for June 8. President Mohammad Khatami is being squeezed between the need to defend reform and the fear of provoking a backlash by hardliners. It is a delicate position, but one Mr. Khatami knows well: Throughout his entire term in office, he has negotiated the treacherous shoals of Iran's domestic politics.

In the last several weeks, dozens of journalists, politicians and supporters of reform have been jailed. Leaders of student groups, one of the president's key constituencies, have been targeted. Earlier this month, the judiciary, which is controlled by hardliners, ordered the arrest of 42 political activists. They were tied to the Iran Freedom Movement, an Islamic progressive opposition group close to reformers; the court also banned all activities by the IFM. The activists are accused of seeking to overthrow the country's Islamic regime, a charge that carries the death penalty. They deny the accusations. The campaign has also extended to the media. Several dozen newspapers and magazines have been closed during the last 12 months; last week, four more received written warnings, which is usually the precursor to being closed.

Many of those arrested are reportedly being held in secret detention centers, where they are denied access to lawyers. Families of detainees have written a letter to the U.N. High Commissioner for Human Rights, accusing the government of the systematic use of psychological pressure on prisoners to extract "confessions" and of making threats against families to silence them.