CAIRO (AP) — One of the top officials in charge of overseeing Egypt’s vote on a contentious Islamist-backed draft constitution resigned Wednesday citing health problems, a judicial official said. The move follows boycotts of the referendum by judges and others that have left the voting process with a severe shortage of monitors to oversee it.

Secretary General of the Election Committee Zaghloul el-Balshi attributed his resignation to “a sudden health crisis,” according to a copy of a letter he sent to the committee that was published by several Egyptian dailies including the privately owned el-Watan.

The official confirmed the authenticity of the letter. Relatives told local Egyptian media that el-Balshi has undergone eye surgery.

“The effort I put in over the past period has caused a sudden health crisis,” the letter of resignation read. “As you know, it is impossible to carry out my mission with this health condition,” it added.

The judicial official spoke on condition of anonymity because he was not authorized to talk to the press.

Many of the country’s judges had boycotted overseeing the referendum. The resulting shortage of supervisors has added to doubts about the vote, the first round of which was held on Dec. 15 and the second round of which is scheduled for Saturday.

El-Balshi had himself threatened to boycott following deadly clashes between liberal and Islamist demonstrators earlier this month, one of several incidents that have increased the sense of crisis in Egypt since President Mohammed Morsi of the Muslim Brotherhood last month issued a decree giving himself wide-ranging powers.

Morsi rescinded the decree, but his move set the scene for further polarization when an Islamist-dominated constitutional drafting panel rushed through the draft of a constitution opposed by liberal parties, secularists, Christians, and many Muslims skeptical of the Brotherhood.

The constitution received 56 percent of the vote in the first round of the referendum. The Brotherhood says the opposition needs to respect the voter majority. His critics say the process has been rushed, the vote was rife with irregularities, turnout was a comparatively low 32 percent, and that a constitution needs consensus, not just a simple majority, to have legitimacy.