From Halopedia, the Halo wiki
The President of the Gao Republic was the senior most position within the government of the Gao Republic.
A collection of holograms related to the Presidents of the Gao Republic existed in the Cabinet Chamber of the People's Palace. It was known as the "People's Collection of Presidential Holographs".
At least fourteen Presidents served the Gao Republic prior to Tejo Aponte in 2553.