The President of Mexico during the Mexican-American War was Antonio López de Santa Anna. He had been a central figure in Mexican politics for decades and had served as President of Mexico multiple times, including during the Mexican-American War from 1846 to 1848. Santa Anna was known for his military leadership and his efforts to modernize Mexico, but he was also criticized for his authoritarian tendencies and his controversial decisions during the war, such as the loss of Texas to the United States.