TEHRAN  More than 20 members of Parliament petitioned their colleagues on Wednesday to impeach the interior minister after investigations indicated that he did not hold several academic degrees that he had claimed.

If the minister, Ali Kordan, is impeached, Parliament will have to hold a vote of confidence on all other cabinet members. According to the Constitution, if 10 cabinet members are dismissed, all members must face a confidence vote.

President Mahmoud Ahmadinejad has dismissed nine cabinet members in the past three years because they disagreed with his policies. No president has faced a confidence vote on the entire cabinet.

Parliament has not yet scheduled a vote on Mr. Kordan’s fate.

The news of the impeachment request comes at a difficult time for Mr. Ahmadinejad, who has faced increasing pressure from the parliamentary opposition in recent months  in part because of complaints over his management of the economy  as well as a revolt by the merchant class over a new sales tax.