In 14 years of governance by the AK Party, there have been one extraordinary congress and five ordinary congresses.
Prime Minister Ahmet Davutoglu called for an extraordinary congress on May 5 and announced that he would not run for the leadership.
On Thursday, the AK Party announced its candidate as the third chairman – and likely, the country’s premier: Minister of Transport, Maritime and Communications Binali Yildirim.
6,000 invitations have been printed for the congress and sent to all the ambassadors in Turkey except those of Egypt, Israel, Bangladesh, Syria and Russia along with a number of nongovernmental organizations, trade unions and political parties with the exception of the People's Democratic Party (HDP).
Nearly 1,470 delegates are expected to elect the party's third chairman of its history. Voting will start at 4 p.m. local time (1300GMT). The previous two were current Turkish President Recep Tayyip Erdogan and Davutoglu.
Extensive security measures have been taken for the congress.