The April 6 Youth Movement (Democratic Front) has called for a boycott of Egypt's presidential election runoff on 16-17 June.
The move came after the April 6 Youth Movement (Ahmed Maher Front) announced it would back the Muslim Brotherhood's Mohamed Morsi against Mubarak's last prime minister Ahmed Shafiq in the runoff.
The Democratic Front, led by Tarek El-Kholi, made the announcement on Wednesday.
In an internal poll, 66 per cent of the front's members called for a boycott, 29 per cent backed Mohamed Morsi and 5 per cent said the front should not announce a position.
The front said it was out of question to back Ahmed Shafiq as he was a member of ousted president Hosni Mubarak's regime.
"Instead of the Mubarak regime being held accountable for the crimes it committed against the Egyptian people, it is trying to find its way back into the presidency," the front said, regarding Shafiq's candidacy.
The April 6 Youth Movement (Ahmed Maher Front) has defended its decision to support Mohamed Morsi in the runoff.
The move was criticised by some observers who linked the move to the nomination of the group's founder, Ahmed Maher, to the constituent assembly.
Ahmed Maher defended the movement's decision on his official Twitter account, insisting the decision to endorse Morsi was taken after surveys and polls within the group.
The presidential runoffs will be held on 16-17 June.
The April 6 Youth Movement (Democratic Front) split from the original April 6 Youth Movement over internal political differences.