Gamal Nassar, a leading member of the Muslim Brotherhood, has resigned from the group's political wing, the Freedom and Justice Party (FJP), citing its "poor performance."
Nassar, the Brotherhood's media advisor from 2002 to 2011 and a founding member of its FJP, announced his resignation late Wednesday via Facebook.
He cited the FJP's poor performance in unifying the country and President Morsi's lack of awareness of the dangers facing the Egyptian people for his decision.
Nassar was the founder and former editor-in-chief of ikhwanonline, the Brotherhood's official website.
He played a significant role in mediating between the Brotherhood and other political groups, particularly leftists.
The Muslim Brotherhood is Egypt's oldest and largest Islamist organisation.