Egyptian Vice President Mahmud Mekki announced his resignation on Saturday, the day of a referendum on a new constitution that leaves unclear whether his position would be maintained.
In a statement obtained by AFP, Mekki said he was stepping down because "political work does not suit my professional character as a judge."
He said he had initially submitted his resignation on November 7, but delayed it until now because of a series of events, including the Israel-Hamas war in Gaza and a decision by President Mohamed Morsi last month to bolster his own powers.
"I saw that today (Saturday) was an appropriate time to announce my resignation as vice president of the republic, and I will continue to volunteer as a soldier," he said.
Mekki, 58, was a respected judge before Morsi named him to the vice presidency in August.
Signup to our newsletter and follow us on Facebook and Twitter!
He led judicial opposition to ousted leader Hosni Mubarak, but eschewed calls to become a presidential candidate himself, saying he wished to stay politically independent.
Mekki had previously intimated to Egyptian media that he considered resigning.
His brother, Ahmed Mekki, is Morsi's justice minister.
Mahmud Mekki was only the second Egyptian vice president in more than 30 years.
Mubarak never filled the post during his three-decade tenure, until he named his intelligence chief, Omar Suleiman, to the job in February 2011, in the midst of the revolt that eventually toppled him.
Born in Alexandria in 1954, Mahmud Mekki studied at the country's police academy and is a former officer in the interior ministry, which he eventually left to join the judiciary.