Estimates range from 70 to 300 thousand people coming all around the country have participated at the rally, which was organized by the Kemalist Thought Foundation (ADD), deriving its name from the modern Turkish Republic's founder Mustafa Kemal Atatürk.
Main opposition People's Republican Party (CHP) and Democratic Left Party (DSP) have also supported the meeting. The demonstrators marched to the mausoleum of Mustafa Kemal Ataturk.
Erdoğan's Islamist background is a main point of opposition for the demonstrators, despite his declaration that "he changed" since the beginning of his Justice and Development Party's (AKP) rule in 2002.
He has yet to say whether or not he will run for the presidency when the AKP-dominated parliament elects a successor to the staunchly secularist Ahmet Necdet Sezer next month.
In an interview with journalists last weekend, Erdogan said he will reveal his decision on April 24, following his conducts with party members and some civil society leaders.
On Saturday's rally demonstrators carried placards reading, "Democracy does not mean tolerating reaction," and "Cankaya (site of the presidential palace in Ankara) will not be home to (religious) sheikhs and brotherhoods."
"Respect faith, reject reaction," another banner read.
While the rally has been criticized for a general tendency to call the army to power to avoid Erdogan becoming a president, the composition of the demonstrators was far from homogeneous.
Thanks to its two-third parliamentary majority, AKP can easily elect the candidate of its choice.
Candidacies can be submitted from this morning to midnight on April 25, and many believe Erdogan will apply for the country's top position.(EÜ)
