Prominent jihadist and al-Qaeda figure Abu Muhammad al-Maqdisi has called the Islamic State's new caliphate a "rush job" and "illegitimate."
A conference held in Amman, Jordan, about Christians and the Arab Spring revealed the many differences between Islamists and Christians over minority rights.
Jordanian Islamists say they will not participate in 23 January legislative election as they are fed up with empty promises and failures of past parliaments.
Representatives of Islamist parties from several Arab countries are in Washington for a conference. They are also holding meetings with U.S. officials.
Jordan's powerful Muslim Brotherhood called for "jihad" against Bashar al-Assad's regime and support for the rebel army, saying it is "an Islamic duty."