Given this paragraph, who was the President of Mexico during the seige of Bexar?
The siege of B��xar (or B��jar) was an early campaign of the Texas Revolution in which a volunteer Texian army defeated Mexican forces at San Antonio de B��xar (now San Antonio, Texas). Texians had become disillusioned with the Mexican government as President and General Antonio L��pez de Santa Anna's tenure became increasingly dictatorial. In early October 1835, Texas settlers gathered in Gonzales to stop Mexican troops from reclaiming a small cannon. The resulting skirmish, known as the Battle of Gonzales, launched the Texas Revolution. Men continued to assemble in Gonzales and soon established the Texian Army. Despite a lack of military training, well-respected local leader General Stephen F. Austin was elected commander.
Based on this text, during the seige of Bexar Antonio Lopez de Santa Anna was the President of Mexico.